sin^4 A - sin^2 A = cos ^4 A - cos^2 A buktikan identitas trigonometri nya

Bab Trigonometri
Matematika SMA Kelas X

sin⁴ a - sin² a = sin² a (sin² - 1)
                      = (1 - cos² a) . (1 - cos² a - 1)
                      = (1 - cos² a) . (-cos² a)
                      = -cos² a + cos⁴ a
                      = cos⁴ a - cos² a

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