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Module 13: Trigonometry with Right Triangles
This Packet Belongs to ________________________ (Student Name) Topic 6: Trigonometry Unit 5β Trigonometry Module 13: Trigonometry with Right Triangles 13.1 Tangent Ratio 13.2 Sine and Cosine Ratios 13.3 Special Right Triangles 13.4 Problem Solving with Trigonometry
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Quick Access to Module Lesson. Click on desired Lesson
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Warm Up Find the missing lengths of the following right Triangles (Hint: use Pythagorean theorem) Find the complementary angles of the following: 4. πβ π¨=ππΒ° __________________________ 5. πβ π©=ππΒ° __________________________ 6. πβ πͺ=ππΒ° __________________________ π=8.94 π=8.66 45Β° π₯=16.64 30Β° 60Β° 3
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Objectives Vocabulary: Assignments: Use Trigonometry ratios
-Trigonometry, Sine, Cosine, Tangent Assignments: 4
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Trigonometry Trigonometry: the study of the relationships between the sides and the angles of triangles. Focusing specifically on right triangles.
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Right Triangle and its Parts
SIX Parts 3 angles 1 right angle (90Β°) 2 acute 3 Sides 1 Hypotenuse 2 legs The hypotenuse is ALWAYS opposite to the right angle and also the largest side. Remember!
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The BIG Three Trig Sine (sin) β like a βsignβ Cosine (cos) βco-signβ
Tangent (tan)
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Sine (sin) Sin of angle X= length of opposite leg of β π₯ length of hypotenuse
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Cosine (cos) Cos of angle X: length of adjecent leg β π₯ length of hypotenuse
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Tangent (tan) Tan of angle X: length of opposite leg β π₯ length of adjacent leg β π₯
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HUMAN Example!
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SOH CAH TOA A A A πΊππ π΄= π π» = πππππ ππ‘π ππ β π΄ βπ¦πππ‘πππ’π π
πΆππ π΄= π΄ π» = ππππππππ‘ ππβ π΄ βπ¦πππ‘πππ’π π ππππ΄= π π΄ = πππππ ππ‘π ππβ π΄ ππππππππ‘ππ β π΄
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π π π» β πΆ π΄ π» π π Include Tangent
= πΈπΉ π·πΈ = 8 15 β0.533 Note: sin and cos are ALWAYS less than 1 Note: Tangent can be either greater or smaller than 1 tan πΉ= πππππ‘β ππ πππ πππππ ππ‘π π‘π β πΉ πππππ‘β ππ πππ ππππππππ‘ π‘π β πΉ = π·πΈ πΈπΉ = 15 8 β1.875
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Note that these are the same
YOUR TURN Directions: Find the THREE trig ratios (sin, cosine, tangent) for the two angles (not including the right angle). Keep as fraction. 9 10.3 πππ πΉ= πππ π·= πΆππ πΉ= πΆππ π·= πππ πΉ= πππ π·= πππ π= πππ π
= πΆππ π= πΆππ π
= πππ π= πππ π
= 5 10.3 3 19.2 Note that these are the same 5 10.3 3 19.2 9 10.3 9/5 19/19.2 5/9 19.2/9
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Using Complementary Angles
Sin A = Cos B π΅=90βπ΄ Sin A = Cos (90-A) How Many Degrees make-up a triangle? Now subtract the right angle
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Using the Calculator TIP!
Make sure your Calculator is in βDegreesβ Then, type the angle measure number value Finally click βsinβ, βcosβ, or βtanβ The number you get is value of the trig value with that angle How to set your calculator to βDegreeββ¦.. -MODE (next to 2nd button) -Degree (third line downβ¦ highlight it) -2nd -Quit Plug everything in BACKWARDS in school calculator TIP!
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Practice the Calculator
Give THREE decimal places Find the πππ 40Β° Find the πΆππ 40Β° Find the Tan 40Β° =0.643 =0.766 =0.839
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This means THREE decimal places
Warm-Up Directions: Find the value of the missing variable. Round to the nearest 100th place. 6= π§ 2 5 π₯ =2.5 3 β =6.12 π‘ 5 = 2.56 This means THREE decimal places π§=12 π₯=2 β=0.49 z=12.8
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Finding a Missing Leg: The Steps
1. DRAW a Visual Picture and Label. 2. Decide which trig function involves the given angle and the given side 3. Set-up the Trig ratio 4. Plug-in the given information 5. Solve for the missing variable. 6. Use the calculator to find the value of the trig function with the given angle 7. Solve Finding a Missing Leg: The Steps
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Finding a Missing Leg: Ex. 1
A. Solve for the length of the Wall. Step 1: is Done Step 2: Decide the trig function to use: Sin Cos Tan Step 3: Set-up the Ratio: SOH CAH TOA sin π΄= πππππ ππ‘π ππ π΄ π» π¦πππ‘πππ’π π Angle Value Step 4: Plug in given information sin 11Β° = πππ π»π¦π = πΆπ΅ πΆπ΄ = π₯ 12 sin 11Β° = π₯ 12
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Finding a Missing Leg: Ex. 1 (cont)
A. Solve for the length of the Wall. sin 11Β° = π₯ 12 Note on Calculator: try to do all the calculator work all at once and round AT THE END Step 5 Solve for missing variable value sin 11Β° = π₯ 12 (12) (12) Include Units in final answer. 12βsin 11Β° =π₯ Step 6: Use calculator to solve everything all at once πβπ π€πππ ππ 2.29 ππππ‘ π‘πππ π₯=2.29 State answer:
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Finding a Missing Leg: Ex. 2
A. Solve for the length of the Floor Step 1: is Done Step 2: Decide the trig function to use: Sin Cos Tan Step 3: Set-up the Ratio: SOH CAH TOA cos π΄= ππππππππ‘ ππ π΄ π» π¦πππ‘πππ’π π Angle Value Step 4: Plug in given information cos 11Β° = πππ βπ¦π = π΄π΅ πΆπ΄ = π¦ 12 cos 11Β° = π¦ 12
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Finding a Missing Leg: Ex. 2 (cont)
A. Solve for the length of the Wall. cos 11Β° = π¦ 12 Note on Calculator: try to do all the calculator work all at once and round AT THE END Step 5 Solve for missing variable value cos 11Β° = π¦ 12 (12) (12) Include Units in final answer. 12βsin 12Β° =π₯ Step 6: Use calculator to solve everything all at once π₯=11.78 State answer: πβπ π€πππ ππ ππππ‘ π‘πππ
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Finding a Missing Leg: Ex. 3
This time, solve for the missing value as an expression The more decimals the more accurate
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Mixed Practice 2. 1. 5. 4. 3. My Answers: 1. 140.04 2. 4.00 3. 57.65
Mixed Practice Round answer to the nearest hundredth. 2. 1. πππ 55Β°= 200 π₯ πππ 30Β°= π₯ 8 5. 3. 4. πππ 70Β°= 11 π₯ πππ 14Β°= π₯ 6 πππ 31Β°= π₯ 12
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YOUR TURN (a) (b) (c) (d) πππ 30Β°= πππ πππ = β 50 β=28.87 ππ‘
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What are they asking for?
Finding a Missing Leg What are they asking for? Step 3: Set-up the Ratio: SOH CAH TOA Given: π΄π΅=6 β π΄=76Β° πππ 76Β°= πππππ ππ‘π ππ β π΄ ππππππππ‘ ππβ π΄ = πΆπ΅ π΄π΅ = πΆπ΅ 6 Step 4-6: Solve for missing Variable THEN plug in πππ 76Β°= πΆπ΅ 6 (6) (6) πβπ»ππ ππΒ°=πͺπ© πΆπ΅=26.06 Step 1: is Done Step 2: Decide the trig function to use: Sin Cos Tan πβπ ππππ‘ππππ ππ π‘βπ ππππ’ππ π‘π π‘βπ πππ£π ππ π‘βπ ππππ ππ ππππ‘.
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Word Problemsβ¦How toβ¦ Read the whole question Draw a picture
Read sentence by sentence Cross out sentences that are useless Do each calculation sentence by sentence Check your answerβ¦Does it make sense?!
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Example 2. Choose Ratio: πππgent 1. Draw 3. Set-up and Solve: πππ 24Β°= πππ πππ = π 1200 a= π¦ππππ
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Practice A ladder 7 m long stands on level ground and makes a 73Β° angle with the ground as it rests against a wall. How far from the wall is the base of the ladder? 1. Draw 2. Choose Ratio: πΆππ‘ππππππ‘ 3. Set-up and Solve: πΆππ 53Β°= πππ βπ¦π = π 1200 g=2.05 π
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Practice A guy wire is anchored 12 feet from the base of a pole. The wire makes a 58Β° angle with the ground. How long is the wire? 1. Draw 2. Choose Ratio: πΆππ‘ππππππ‘ 3. Set-up and Solve: πΆππ 58Β°= πππ βπ¦π = π€ 12 π€=22.65 ππ‘
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Practice To see the top of a building 1000 feet away, you look up 24Β° from the horizontal. What is the height of the building? 1. Draw 2. Choose Ratio: πππππππ‘ 3. Set-up and Solve: πππ 24Β°= πππ πππ = π 1000 π= ππ‘
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What is Radians? Radians are like degrees except with a different unit
Conversion like feet to inches The unit it Pi π=180Β° Questions with radians will ask you to set up the ratio without solving
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SWITCH CALCULATOR MODE!!!
Radian Practice SWITCH CALCULATOR MODE!!! πππ 2π 7 = π₯ 4 Cos π 5 = 10 π₯
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Dealing with Radians Two Options:
1. Change mode of calculator to radians. 2. Convert radians to degrees, then complete calculation using degrees. How to Convert Radian to Degrees (not going to be tested, but you may have to do it to complete a question): Radians to Degrees Degrees to Radians Multiply by 180 π Multiply by π 180 Plug in 180 where you see π & vice-versa TIP!
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13.1-13.2 Classwork/Homework Starts on Page 582
Handout
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Using Trigonometry Ratios to find Missing Angles
Objectives -Find the angle of Elevation or Depression in a Right Triangle Vocabulary: - Angle of Elevation and Angle of Depression Assignments:
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Angle of Elevation VS Depression
Definition of Angle of Elevation. The word "elevation" means "rise" or "move up". Angle of elevation is the angle between the horizontal and the line of sight to an object above the horizontal 2. Definition of Angle of Depression. The word "depression" means "fall" or "drop". Angle of depression is the angle between the horizontal and the line of sight to an object beneath the horizontal. Take a look at the example below.
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Missing Angle/Inverse
These questions do not ask for the side length, they give you the sides but they ask for the angle measure These questions require using the INVERSE of sin, cos or tan. The inverse gives us the value of the angle measure A sin β1 πππ βπ¦π =π΄ ππ¨π¬ β1 πππ£ βπ¦π =π΄ ππ π§ βπ πππ πππ£ =π΄
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Finding the Missing Angle: The Steps
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Using the Calculator for ANGLE
Make sure your Calculator is in βDegreesβ Then, type the angle measure number value Click βSHIFTβ Choose and click Sin, Cos, Tan For ANGLE measure always use SHIFT, function TIP!
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This means TWO decimal places
Warm-Up Directions: Find the value of the missing variable. Round to the nearest 100th place. sin β1 (0.54) cos β1 (0.1234) tan β1 (1.76) sin β1 (0.135) This means TWO decimal places =32.68 =82.92 =60.40 =7.76
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Word Problemsβ¦How toβ¦ Read the whole question Draw a picture
Read sentence by sentence Cross out sentences that are useless Do each calculation sentence by sentence Check your answerβ¦Does it make sense?!
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If you know that you are looking for an ANGLE, jump to this step.
1. Draw Example 2. Choose Ratio: πππππππ‘ 3. Set-up and Solve: πππ π= πππ πππ = 40 36 If you know that you are looking for an ANGLE, jump to this step. πππ π= ππ π β1 ( ) ππ π β1 ( ) π=ππ π β π=48Β° SHIFT, TAN
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1. Draw π΅ πΆ 2 +π΄ πΆ 2 =π΄ π΅ 2 π΅ πΆ 2 + 7 2 = 9 2 π΅ πΆ 2 +49=81 π΅ πΆ 2 =32
Pythagorean Theorem π΅ πΆ 2 +π΄ πΆ 2 =π΄ π΅ 2 π΅ πΆ = 9 2 π΅ πΆ 2 +49=81 π΅ πΆ 2 =32 π΅ πΆ 2 = 32 β5.66 Several options available πβ π΅=51Β° πβ π΄=39Β°
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Space to work on Previous Problem
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Mixed Practice
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Objectives Vocabulary Assignments:
- Understand the relationships between 45Β°β45Β°β90Β° and 30Β°β60Β°β90Β° triangles Vocabulary N/A Assignments:
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Special Right Triangles
There are TWO special Right Triangles that have special lengths for the hypotenuse and the two legs If the triangle shows whether one 30Β° or one 60Β° , it is the Remember!
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45Β°-45Β°-90Β° Special Right Triangle
In a triangle 45Β°-45Β°-90Β° , the hypotenuse is 2 times as long as a leg. Example: 45Β° 45Β° cm Hypotenuse 5 cm Leg X X 45Β° 5 cm 45Β° Leg X
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30Β°-60Β°-90Β° Special Right Triangle
In a triangle 30Β°-60Β°-90Β° , the hypotenuse is twice as long as the shorter leg, and the longer leg is 3 times as long as the shorter leg. Example: Hypotenuse 30Β° 2X Long Leg 30Β° 10 cm X cm 60Β° 60Β° X Short Leg 5 cm
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What kind of angles are made by the diagonals in a square?
Take a Square Find the Diagonal Find its Lengths d π₯ 2 + π₯ 2 = π 2 x 2 π₯ 2 = π 2 2 π₯ 2 = π 2 2 π₯ 2 = π 2 2 βπ₯=π x What kind of angles are made by the diagonals in a square? Moody Mathematics
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45o-45o-90o legβ 2 leg leg
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Example: Find the value of a and b.
b = cm 45Β° 7 cm 45Β° x b x 45 Β° 45Β° a = 7 cm a x Step 1: Find the missing angle measure. 45Β° Step 2: Decide which special right triangle applies. 45Β°-45Β°-90Β° Step 3: Match the 45Β°-45Β°-90Β° pattern with the problem. Step 4: From the pattern, we know that x = 7 , a = x, and b = x . Step 5: Solve for a and b
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45o-45o-90o Moody Mathematics
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What kind of angles are made by the diagonals in a square?
Take an Isosceles Triangle Find the Draw the altitude Find its Lengths 2x 2x π 2 + π₯ 2 = (2π₯) 2 d π 2 + π₯ 2 = 4π₯ 2 π 2 =3 π₯ 2 π= 3 β π₯ 2 2x π= 3 βπ₯ π π What kind of angles are made by the diagonals in a square? Moody Mathematics
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30o-60o-90o Short Leg Hypotenuse 60Β° 30Β° Long leg
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30o-60o-90o Short Leg 60Β° 2βShort Leg 30Β° Short Leg . 3
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Example: Find the value of a and b.
b = 14 cm 60Β° 7 cm 30Β° 2x b 30 Β° 60Β° a = cm a x Step 1: Find the missing angle measure. 30Β° Step 2: Decide which special right triangle applies. 30Β°-60Β°-90Β° Step 3: Match the 30Β°-60Β°-90Β° pattern with the problem. Step 4: From the pattern, we know that x = 7 , b = 2x, and a = x . Step 5: Solve for a and b
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30o-60o-90o Moody Mathematics
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45Β°-45Β°-90Β° Special Right Triangle
In a triangle 45Β°-45Β°-90Β° , the hypotenuse is 2 times as long as a leg. Example: Leg 45Β° X 45Β° 5 cm cm Hypotenuse X Leg X 45Β°
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30Β°-60Β°-90Β° Special Right Triangle
In a triangle 30Β°-60Β°-90Β° , the hypotenuse is twice as long as the shorter leg, and the longer leg is 3 times as long as the shorter leg. Note: sometimes the triangle is rotated! Example: Hypotenuse 30Β° 2X 10 cm 5 cm cm Long Leg 30Β° X 60Β° X Short Leg 60Β°
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Mixed Practice: Moody Mathematics
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This means that: sin 30Β° = πππ βπ¦π = 5 3 10 3 = 5 10 = 1 2
10 3 15 This means that: sin 30Β° = πππ βπ¦π = = 5 10 = 1 2 What is sin 60Β° ? This means that: cos 30Β° = πππ βπ¦π = = What is cos 60Β° ?
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