How do you prove cos (2x) / (1-sin 2x) = (1 + tan 2x) / (1-tan 2x)cos(2x)1sin2x=1+tan2x1tan2x?

1 Answer
Aug 12, 2015

(cos 2x)/(1-sin 2x) ne (1+tan 2x)/(1-tan 2x) cos2x1sin2x1+tan2x1tan2x

Explanation:

Assume that (cos 2x)/(1-sin 2x) = (1+tan 2x)/(1-tan 2x) cos2x1sin2x=1+tan2x1tan2x is true for all xx

Taking 2x = pi/4 2x=π4

LHS: cos(pi/4)/(1-sin(pi/4)) = sqrt(2)/(2-sqrt(2)) cos(π4)1sin(π4)=222
RHS: lim_(2x rarr pi/4) (1+tan(2x))/(1-tan(2x)) = oo

Therefore (cos 2x)/(1-sin 2x) ne (1+tan 2x)/(1-tan 2x)