Diketahui cos (a + b) = 1/2 dan cos (a - b) = 1/8. Nilai dari (sin a + sin b) = . . . .

Cos(a+b)=1/2
sinA.sinB-cosA.cosB=1/2...(1
Cos(a-b)=1/8
sinA.sinB+cosA.cosB=1/8...(2
eleminasi 1 dan 2
sinA.sinB-cosA.cosB=1/2
sinA.sinB+cosA.cosB=1/8
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2sinA.sinB=1/2+1/8
sinA.sinB=5/8/2=5/8x1/2=5/16