7.3 Finding Missing Parts Objectives: • Write trigonometric ratio’s • Use trig to solve for a missing side • Use trig to solve for a missing angle
Concept: Quick Review hypotenuse hypotenuse opposite opposite adjacent
Concept: Quick Review cont… Find the sine, the cosine, and the tangent of theta 24.5 8.2 23.1 Shrink yourself down and stand where the angle is. Now, figure out your ratios.
tan Concept: Finding Sides ) 20 m x 20 55 Ex: 1 Figure out which ratio to use. Find x. Round to the nearest tenth. 20 m x Now, figure out which trig ratio you have and set up the problem. Shrink yourself down and stand where the angle is. Cross multiply to solve for x. tan 20 55 )
tan Concept: Finding Sides cont… ( ) = 80 ft x 80 72 ) 2. Now, figure out which trig ratio you have and set up the problem. Shrink yourself down and stand where the angle is. 3. Cross Multiply 4. Divide by tan (72) tan 80 ( 72 ) ) =
Concept: Finding a Missing Angle Concept: Finding a Missing Angle Steps to finding the missing angle of a right triangle using trigonometric ratios: Draw the figure and mark on it HYP, OPP, ADJ relative to the unknown angle OPP Ø 5.92 km ADJ 2.67 km HYP
Concept: Finding a Missing Angle Concept: Finding a Missing Angle Steps to finding the missing angle of a right triangle using trigonometric ratios: For the unknown angle choose the correct trig ratio which can be used to set up an equation Set up the equation OPP Ø 5.92 km ADJ 2.67 km HYP
Concept: Finding a Missing Angle Concept: Finding a Missing Angle Steps to finding the missing angle of a right triangle using trigonometric ratios: Solve the equation to find the unknown using the inverse of trigonometric ratio. OPP Ø 5.92 km ADJ 2.67 km HYP 2nd cos ( 2.67 ÷ 5.92 ) ENT
Concept: Finding a Missing Angle Your turn Practice Together: Ø 3.1 km 2.1 km Find, to one decimal place, the unknown angle in the triangle. Ø = 34.1º
Concept: Finding a Missing Angle Your turn Practice Alone: Find, to 1 decimal place, the unknown angle in the given triangle. Ø 9 m 4 m Ø = 26.4º
Now go and practice. Remember, practice makes permanent! Homework: PM 9.4 IXL-A2:Y.1 Now go and practice. Remember, practice makes permanent!