buktikan bahwa 4 cos² a+2 = 6-4 sin² a

4cos^2a + 2 = 6 - 4sin^2a
4cos^2a + 4sin^2a = 6 - 2
4(sin^2a + cos^2a) = 4
4x1 = 4, terbukti..

4 cos^2 a + 2
= 4(1 - sin^2 a) + 2
= 4 - 4 sin^2 a + 2
= 6 - 4 sin^2 a