How do you prove $cos^2phi/cos^2theta=(1+cos2phi)/(1+cos2theta)$ ?

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Answer 1 · 2016-10-05T18:42:48

see below

$cos^2 phi/cos^2 theta = (1+cos 2 phi)/(1+cos2theta)$

Right Side: $= (1+cos 2 phi)/(1+cos2theta)$

$=(1+2cos^2phi-1)/(1+2cos^theta-1)$

$=(2cos^2 phi)/(2cos^2theta)$

$=cos^2phi/cos^2theta$

$=$ Left Side

How do you prove cos^2phi/cos^2theta=(1+cos2phi)/(1+cos2theta)cos^2phi/cos^2theta=(1+cos2phi)/(1+cos2theta)?