It ain't so. Note that for x =0, you get



So the identity is incorrect.

verify cosx + sinx tanx=secx

Quote:

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Originally Posted by cgamboa2412

verify cosx + sinx tanx=secx

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In the furture please do not tag a new question onto an old post. Start a new thread instead.

This identity can be proved by replacing the tan(x) function with sin(x)/cos(x) and then combining the left hand side into a single fraction. Finally recall that cos^2x + sin^2x = 1.