Inverses of Trigonometric Functions Use the inverses to find the angle measures when we are given two side lengths. Here's how to do it on your calculator: We also know this to be true because on the unit circle, sin(30) = 1/2 So, let's practice this... Neat, but it gets a little more complicated.

On our unit circle, we know that the y-values are also the sine values. And there are two angles on the unit circle that have a sine (y-value) which equals 1/2. So, here is what we can say... Since we can have more than one answer, we have to make like a little easier and restrict it so that we only get one answer.

The way that we do that is by capitalizing our trig functions. You'll notice in the last examples we have been writing sine and cosine using lower case letters. When we use uppercase letters, that means there is only one possible answer. That looks like this: These circles represent the part of the unit circle that the answer can come from. So when we have a capitalized cosine, the answer can only be between 0 and 180 degrees. Don't really worry about this column. We only really care about this column. Homework:

pg. 953 #16-31, 39-41 1. 36.9 degrees

2. 64.2 degrees

3. 25.4 degrees

4. 59.0 degrees Answer:

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# Inverses of Trigonometric Functions

Algebra II
Section 13.4

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