Question

If cscθ = 1 1/4, then cosθ = _____.
±3/4
±4/5
±3/5
±1 3/2

Answer 1

±3/5.

Explanation:

sinθ = 1/ csc θ

= 1 / 1 1/4

= 1 / 5/4

= 4/5.

Here we have a 3-4-5 right triangle with θ opposite the longest leg.

So cos θ = 3/5.

Also if θ is in the second quadrant the cosθ = -3/5.