cos2a/tan(π/4+a),

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cos2a/tan(π/4+a),
cos2a/tan(π/4+a),

cos2a/tan(π/4+a),
cos 2a=cos² a - sin² a=(cos a+sin a)(cos a - sin a)
tan (π/4+a)=(tan π/4 + tan a)/(1 - tan π/4 x tan a)
=(1+tan a)/(1- tan a)
=(cos a +sin a)/(cos a - sin a)
cos2a/tan(π/4+a)=[(cos a+sin a)(cos a - sin a)]/[(cos a +sin a)/(cos a - sin a)]
=(cos a - sin a)²
=cos² a + sin² a- 2 cos a sin a
=1- sin 2a

=(cos^a-sin^a)*(1-tan(pai/4)*tan(a))/tan(pai/4)+tan(a)
=(cos^a-sin^a)*(1-tan(a))/(1+tan(a))
=(1-tan^a)(1-tan(a))/(1+tan(a))*cos^a
=(1-tan(a))^/cos^a