Prove that tan(θ)+cot(θ)sec(θ)=csc(θ)\frac{\tan(\theta) + \cot(\theta)}{\sec(\theta)} = \csc(\theta)sec(θ)tan(θ)+cot(θ)=csc(θ).
True; this identity holds for all θ\thetaθ where defined
False; this is not a valid identity
True; but only for acute angles θ\thetaθ
True; but only for θ∈(0,π)\theta \in (0, \pi)θ∈(0,π)