1/2√3 sin x + 1/2 cos x =…… A. Cos ( x- 60° ) B. -cos ( x+ 60°) C. Sin (x +60°) D. Sin ( x-60° ) E. Cos (x+60°)

Trigonometri
bentuk a cos x +  b sin x = k. cos (x + c)

1/2 √3  sin x + 1/2 cos x = 
atau
1/2 cos x + 1/2 √3 sin x  = a cos x + b sin x
a = 1/2
b= 1/2 √3
k² = a²+b² --> k² = 1/4 + 3/4 = 1
k = 1

tan c = b/a = (1/2 √3)/(1/2) = √3  = tan 60
c= 60
 1/2 √3 sin x + 1/2 cos x = k cos (x - c)
1/2 √3 sin x + 1/2 cos x = 1 cos (x - 60) = cos (x-60)