Warm up 100 ft x 45° 51.3° Find x. Round to the nearest foot. x = 25 ft

Lesson Inverse Trig Functions SWBAT use the inverse of sin, cos and tan to solve for a missing angle in a right triangle.

Trig – Inverse Functions ∆ It is possible to determine the size of either acute angle in a right triangle if you know the lengths of any 2 sides of that triangle. ∆ To do this, you use the inverse function sin -1 cos -1 tan -1  Find them on your calculator – you must push the 2 nd button first  Anytime you use INVERSE trig you are finding an ANGLE

Let’s look at some examples ∆Example 1: solve for x To get x alone you do the opposite of tan/sin/cos which is the inverse – tan -1 /sin -1 / cos -1 Don’t forget the degree sign

Let’s look at some examples ∆Example 2: solve for x To get x alone you do the opposite of tan/sin/cos which is the inverse – tan -1 /sin -1 / cos -1

Story Problems ∆ Step 1 – Write an equation that represents the trig ratio. ∆ Step 2 – Find the angle that has an approximate tangent value of (8/15) using your calculator (inverse tangent). 15 in 8 in x (opp) ( adj ) ∆ When using your calculator, calculate the inverse tan – (2nd, tan, 8/15, enter). Or you can use your trig table sheet, working backwards. (in the tan column look for the value of 8/15 ( ), once you find it look back to the angle measure for that value)

Inverse Functions ∆Ex 4. ∆Step 1 – ∆Step 2 - x 15 cm 18 cm

Summary ∆How are the trig functions we learned about yesterday related to the ones we talked about today? Show how they are related.

Homework ∆WS