nilai dari 4 sin 37 1/2 * sin 127 1/2 =

4 sin37,5° * sin(180-127,5)°
=4 sin 37,5° * sin 52,5°
=4 sin 37,5° * cos (90°-52,5)°
=4 sin 37,5° * cos 37,5°
=2 sin 2(37,5)°
=2 sin 75°
=2 sin(30+45)°
=2 (sin 30° cos 45° + cos 30° sin 45°)
=2 ((1/2)(1/2 √2)+(1/2 √3)(1/2 √2))
=2(1/4 √2 + 1/4 √6)
=1/2 √2 + 1/2 √6