Diketahui (A + B) =phi/3 dan sinA sinB =1/4 . Nilai dari cos (A – B) =....
FLXcahayadi
Cos (A-B) = cos A . cos B + sin A . sin B cos (A-B) = ½cos(A-B) + ½cos(A+B) +1/4 cos(A-B) - ½cos (A-B) = ½cos (π/3) + 1/4 ½cos (A-B) = (1/2)(1/2) + 1/4 cos (A-B) = 2 (1/4 + 1/4) coa (A-B) = 1
cos (A-B) = ½cos(A-B) + ½cos(A+B) +1/4
cos(A-B) - ½cos (A-B) = ½cos (π/3) + 1/4
½cos (A-B) = (1/2)(1/2) + 1/4
cos (A-B) = 2 (1/4 + 1/4)
coa (A-B) = 1