Question

How to do this problem

Answer 1

One way in which to approach this proof would be to convert 

1                       (cos x)^2
------------- into ---------------- .  Next, note that 1 - (sin x)^2 = (cos x)^2
(tan x)^2           (sin x)^2         and that 1 - (cos x)^2 = (sin x)^2.

Then we have:

(cos x)^2        (cos x)^2
-------------  = --------------------  which is a true equation
(sin x)^2         (sin x)^2