This document discusses trigonometric identities and how to prove trigonometric statements. It covers basic trigonometric ratios and inverse ratios. It then presents three important trigonometric identities: 1) sin^2(θ) + cos^2(θ) = 1, 2) 1 + tan^2(θ) = sec^2(θ), and 3) 1 + cot^2(θ) = csc^2(θ). It provides examples of proving identities by simplifying expressions using basic identities, operations, and factoring. It also includes sample exam questions on proving an identity and determining an equivalent expression for tan(A) + cot(A).