Question

Can someone solve this and explain it in steps to someone that have never learned this?

Answer 1

Explanation:

in third quadrant sin is negative.

sin² θ+cos² θ=1

sin²θ+(-16/20)²=1

sin²θ+(-4/5)²=1

sinθ=±√(1-16/25)

=±√((25-16)/25)

=±√(9/25)

=±3/5

so

sin θ=-3/5