Sin^4a+cos^2a+sin^2a*cos^2a упростить

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