Question

довести тотожність cos^4a+sin^2a+cos^2a*sin^2a​=1

Answer 1

cos^4a+sin^2a+cos^2a*sin^2a​=1

cos^4a+sin^2a+cos^2a*(1-cos^2a) = cos^2a + sin^2a

cos^4a + sin^2a - sin^2a + cos^2a - cos^4a = cos^2a

cos^2a = cos^2a