Page 20 - Ebook Trigonometri_Krisna Hasugian_MESP 2019

Find an angle measure using trig functions

Wait a minute, what happens if you have the trig ratio, but you are asked to find
the angles measure? Grab your TI Graphing calculator and notice that above the

sin, cos, and tan buttons, there is , , . These are your inverse
−1
−1
−1
trigonometric functions, also known as arcsine, arccosine, and arctangent. If you
use these buttons in conjunction with your trig ratio, you will get the angle
measure for !

Let’s see some examples of this.

Example 18 8
We know that tan =
6
nd
So to find the value of θ, press 2 tan on your calculator
and then type in (8/6)
8
( ) ≈ 53.13
−1
6
≈ 53.13°

How about another

Example 19
We are given information about the adjacent side and the
hypotenuse, so we will use the cosine function
1
cos =
2
1
( ) = 60
−1
2

= 60°

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