Nilai dari sin^2 15° + sin^2 75°

Nilai fungsi trigonometri

sin² 15 + sin² 75 = (sin 15 + sin 75)² – 2 sin 75 sin 15
sin² 15 + sin² 75 = [(2 sin 1/2(75+15) cos 1/2(75-15)]² + [cos (75+15) – cos(75-15)]
sin² 15 + sin² 75 = [ 2 sin45 cos 30]² + [ cos 90 – cos 60]
sin² 15 + sin² 75 = [ 2(1/2 √2)(1/2√3]² + 0 – 1/2
sin² 15 + sin² 75 = (4(1/4)(2)(1/4)(3)) – 1/2 = 3/2 – 1/2 = 2/2 = 1