How to Prove Trigonometric Identities

This trigonometry lesson shows you how to prove intermediate problems on solving trigonometric identities. On solving trig identities, mastery of your algebra skills is a must. There are some techniques in simplifying trig identities which require to simplify rational expressions and even factoring trig expressions similar to some algebraic expressions. 00:42 sec x – tan x sin x = 1 / sec x 03:06 (1+cos x) / sin x = csc x + cot x 04:12 (sec x sin x) / (tan x + cot x) = sin^2 x 07:35 sec B / cos B – tan B / cot B = 1 11:23 cos^2y – sin^2y = 1 – 2sin^2y 12:34 csc^2 c tan^2x – 1 = tan^2 x 14:40 (tan x / sec x) + (cot x / csc x) = sin x + cos x 18:18 (sin x + cos x) (tan x + cot x) = sec x + csc x