You can solve for theta by taking the . Then just plug in theta as the parameter for sin().
Dear momuvfour,
It is given that That is theta is in the second or third quadrants. Hence we have to find values for such that theta will be in the second or third quadrants. Can you continue from here??
Dear macosxnerd101,
By taking you have only considered the case where theta is in the second quadrant.
Hope this will help you.