Question

What signs are cos( -80)
and tan ( -80)

Answer 1

Assuming degrees:

- cos(−80°) = cos(80°) (cos is even) → positive.
- tan(−80°) = −tan(80°) (tan is odd) → negative.

(Reason: cos(−θ)=cosθ, sin(−θ)=−sinθ, so tan(−θ)=−tanθ.)