Question

Sec x tan x (1-sin^2 x) = __x I need help solving this I have no idea.

Answer 1

Recall that secx is the reciprocal of cosx.
Also, recall the property:
$cos^{2}x + sin^{2}x = 1$

$\therefore cos^{2}x = 1 - sin^{2}x$

Thus, we can rewrite the equation as:
$secx tanx (1 - sin^{2}x) = secx tanx cos^{2}x$
$= tanx cosx$
$= \frac{sinx}{cosx} \cdot cosx$
$= sinx$