Jika sin x-cos x=1/4,maka nilai 8 sin x.cos x adalah

(sin x-cos x)² = (1/4)²
sin²x – 2sin x. cos x + cos²x = 1/16
-2sin x. cos x = 1/16 – 1
2sin x. cos x = 15/16
8sin x. cos x = 15/4