Tolong dong tugas mtk kls 11

2 cos 15 (sin 15 + cos 15) - 1 =
= 2cos15sin15 + 2cos^2 15 - 1
= sin 2(15) + 2 [cos(45-30)]^2 - 1
= sin30 + 2[cos45cos30 + sin45sin30]^2 - 1
= 1/2 + 2[(1/2 √2)(1/2 √3) + (1/2 √2)(1/2)]^2 - 1
= -1/2 + 2[1/4 √6 + 1/4 √2]^2
= -1/2 + 2[6/16 + 2/16 + 2/16 √12]
= -1/2 + 2[1/2 + 1/4 √3]
= -1/2 + 1 + 1/2 √3
= 1/2 + 1/2 √3
= 1/2[1+√3]

Semoga membantu, tetap semangat
Salam, Jkira