Question

decide whether the following equation is a trigonometric identity. explain your reasoning.

cos^2 x(1+tan^2x)=1

Answer 1

It is true

Answer 2

consider left hand side
cos^2x(1+tan^2x)
cos^2x(sec^2x)
cos^2x (1/cos^2x)
1

Answer 3

so we have this identity

Answer 4

thanks!