Question

1-tan square thita/1+tan square thita=cos square thita-sin square thita​

Answer 1

1-tan^2o / 1+tan^2o = cos^2o-sin^2o

(1-sin^2o/cos^2o)/(1+sin^2o/cos^2o) = RHS

(cos^2o - sin^2o/cos^2o)/(cos^2o+sin^2o/cos^2o)= RHS

cos^2o-sin^2o/cos^2o)(1/cos^2o =RHS

cos^2o-sin^2o /cos^2o× cos^2o/1=RHS

cos^2-sin^2o = cos^2 - sin^2o

hence proved

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