Question

If `cotx= -3/4` and `90<x<180`, what is sinx?

Answer 1

Use the trig identity:

`sin^2 x = 1/(1 + cot^2 x) = 1/(1 + 9/16) = 16/25 --> sin x = +- 4/5 = +-0.8`

Since 90 < x < 180, and x is in Quadrant II, then sin x is positive -> sin x = 0.8