If sin theta =4/5& theta is not Frist quadrant ,find the value of cos theta?

1 Answer
Jun 20, 2018

cos t = -3/5

Explanation:

sin t = 4/5. Angle t is not in Quadrant 1.
cos^2 t = 1 - sin^2 t = 1 - 16/25 = 9/25
cos t = +- 3/5
Since t isn't in Quadrant 1, hence, it lies in Quadrant 2, and cos t is negative.
cos t = -3/5