SOLUTION: If the point P begin ordered pair negative fraction numerator 3 over denominator 5 end fraction comma y end ordered pair lies on the unit circle and P is in the second quadrant, wh

Algebra ->  Trigonometry-basics -> SOLUTION: If the point P begin ordered pair negative fraction numerator 3 over denominator 5 end fraction comma y end ordered pair lies on the unit circle and P is in the second quadrant, wh      Log On


   

Question 990339: If the point P begin ordered pair negative fraction numerator 3 over denominator 5 end fraction comma y end ordered pair lies on the unit circle and P is in the second quadrant, what does y equal?
Answer by josgarithmetic(39630) About Me  (Show Source):
You can put this solution on YOUR website!
(-3/5,y) on the UNIT CIRCLE; what is y?

The x and y coordinate values are the cosine and sine function values, and you have the Pythagorean Theorem relationship, cos%5E2%28theta%29%2Bsin%5E2%28theta%29=1. No real concern needed for theta, just that you have the cosine value given but want to find the y value for the point on the unit circle. Here, this means to find y or the SINE of the angle. You want the POSITIVE value because, "second quadrant" or quadrant Number 2.

cos%28theta%29=-3%2F5; now use the identity to calculate sin%28theta%29.