nyataka dalam bentuk paling sederhana: a.Sin 75° + Sin 15°
b.Cos 100° + cos 20°

Trigonometri

Hmm.. takut nya gak paham lg :(

sin a + sin b = 2 sin (a+b)/2 cos (a-b)/2
cos a + cos b = 2 cos (a+b)/2 cos (a-b)/2

••
sin 75 + sin 15
= 2 sin (75+15)/2 cos (75-25)/2
= 2 sin 45° cos 25°
= √2 cos 25° ✓

cos 100 + cos 20
= 2 cos (100+20)/2 cos (100-20)/2
= 2 cos 60° cos 40°
= cos 40° ✓