dik α+β=π/3 dan sinαsinβ=1/4 nilai dari cos (α-β)=

cos (α-β) = cosαcosβ + sinαsinβ
= cosαcosβ + ¼

cos (α+β) = cosαcosβ - sinαsinβ
cos π/3 = cosαcosβ - ¼
½ = cosαcosβ - ¼
¾ = cosαcosβ

cos (α-β) = cosαcosβ + sinαsinβ
= cosαcosβ + ¼
= ¾ + ¼
= 1 ✔️

semoga jelas dan membantu

sin a sin b = 1/4
sin a sin b = 1/2 (cos (a-b)) - 1/2(cos(a+b))
1/4 = 1/2 (cos(a-b)) - 1/2 (cos (π/3))
1/4 = 1/2 (cos(a-b)) - 1/2 (1/2)
1/4 = 1/2 (cos(a-b)) - 1/4
1/4 + 1/4 = 1/2 (cos(a-b))
1/2 = 1/2 (cos(a-b))
cos(a-b) = 1

semoga benar dan bermanfaat