[tmoz:425708] Re: iki trigonometri sorusu

sin ^4(15)+cos^4(15)=
(sin^2(15) + cos^2(15))^2 - 2 sin^2(15).cos^2(15)
= 1^2 - 2.(2/2sin15.cos15)^2 = 1 - 2.(sin30 / 2)^2 = 1 - 2. (1/4)^2 =
7/8

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