Question

How do you prove `cosx= 1/(cosx-sinx tanx)`?

Answer 1

`R.H.S=L.H.S (proved)`

Explanation:

I assume the minus sign in denominator is incorrect. It should be + sign instead of - sign. Then
RHS = `1/(cosx + sinx. sinx/cosx) = (1)/((cos^2x+sin^2x)/cosx) = cosx/(cos^2x+sin^2x) = cosx :. R.H.S=L.H.S (proved)`

`where:`

`cos^2x + sin^2x =1`