Question

What basic trigonometry identity would you use to identify that sin x cos x tan x = 1 - cos^2x

Answer 1

tanx = sinx/cosx

Explanation:

Given the expression

sin x cos x tan x = 1 - cos^2x

According to trigonometry identity

tan x = sinx/cosx

Substitute into the expression. From LHS

sin x cos x tan x

= sin x cos x (sinx/cosx)

= sin²x

Also since sin²x+cos²x = 1

Hence sin²x = 1 - cos²x (RHS)

The correct option is therefore tanx = sinx/cosx