nilai sin 150°+cos 15=

sin(180-30) + cos(45-30)
= sin30 + cos45 cos30 - sin45 sin30
= 1/2 + (1/2)(√2)(1/2)√3 - (1/2)(√2)(1/2)
= 1/2 + (1/4)√6 + (1/4)√2
= (1/4)(2 + √6 + √2)

sin 105° + cos 15° = sin (90°+15°) + cos 15°
sin 105° + cos 15° = cos 15° + cos 15°
sin 105° + cos 15° = 2 cos 15°
sin 105° + cos 15° = 2 cos (45°-30°)
sin 105° + cos 15° = 2 (cos 45° cos 30° + sin 45° sin 30°)
sin 105° + cos 15° = 2 (1/2√2. 1/2√3 + 1/2√2.1/2)
sin 105° + cos 15° = 1/2√6 + 1/2√2
sin 105° + cos 15° = 1/2(√6 + √2)