Question

Find cos theta if sin theta = 3/5 and 90 degrees<theta<180 degrees.

Is the answer -sqrt34/5?

Appreciate you checking my anwers.

Answer 1

cos is - in second quadrant
this is a 3,4,5 right triangle but anyway
3^2 + x^2 = 25
x^2 = 16
x = 4 but actually -4 because in quadrant 2
cos t = -4/5