7-4

So this week I'm going over a section we learned in chapter 7. Reference angles are just like reduced fractions. The purpose of them are to make an angle you have bigger than what you need and and shrink it. The steps for making a reference angle are as follows:

1. Find the original quadrant

2. Determine if the angle is a positive or negative angle ( you have to refer back to the unit circle for this)

3. Subtract 360 degrees or 90 degrees until you get the angle between 0 degrees and 90 degrees

Example timeeee!!!!

Example 1: Find the refernce angle of sin 695 degrees

First you have to find out which quadrant 695 degrees lies in.

sin 695 degrees lies in quadrant 4

Now using the unit circle we have to determine if sin 695 degrees is positive or negative

Since sin = y/r the y in the angle is negative

Sin 695 degrees is negative

Now you will subtract 360 degrees until you get the angle between 0 and 90 degrees

sin 695 degrees = -sin 25 degrees

Example 2: Find the refernce angle of cos 725

cos 725 degrees lies in quadrant 1

cos 725 degrees is positive

cos 725 degrees = cos 5 degrees

Welp, that's it!!(: