The Unit Circle :)

This week in class we learned about the unit circle. The unit circle is a circle with a center at the origin or (0,0) and a radius of one. To use the unit circle, you first have to figure out which trig function you are using and plug it into the formula. Each trig function has a different formula.

Sin-y/r

Cos-x/r

Csc-r/y

Sec-r/x

Tan-y/x

Cot-x/y

For example if you were trying to find sin 90 degrees you would look at your unit circle and find 90 degrees at (0,1). Then you would plug it into your formula for sin, which is y/r, and you’d put one for your r and one for your y. So your answer would be one/one, which is one. If you were to get a zero in the top of your fraction or your numerator then you answer would be zero. Although if you were to get a zero in the bottom of your fraction or your denominator, then your answer would be undefined. If you get a negative degree then you would go counter clockwise around the circle instead of clockwise. For example if you were trying to find sin –90 degrees then your answer would be negative one/one, which is negative one. If your degree value is greater than 360 then you would have to find a reference angle.