Prove that
Using cos(90° + θ) = - sinθ(I quadrant cosx is positive
cosec( - θ) = - cosecθ
tan(270° - θ) = tan(180° + 90° - θ) = tan(90° - θ) = cotθ
(III quadrant tanx is positive)
Similarily sin(270° + θ) = - cosθ (IV quadrant sinx is negative
cot(360° - θ) = cotθ(IV quadrant cotx is negative)