Write the first trigonometric function in terms of the second for θ in the given quadrant. cos(θ), sin(θ); θ in Quadrant III

Answer 1

cos² θ = 1 - sin² θ

cos θ = ±√(sin² θ)

In QIII cos < 0

Answer 2

Lets go with 1°. In the 3rd quad you have 181°.

cos=.999847...... cos=-.999847................

sin=.01745........ sin=-17.452.................