Question 990339
(-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^2(theta)+sin^2(theta)=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(theta)=-3/5}}}; now use the identity to calculate {{{sin(theta)}}}.