Question

Sa se caluleze suma S=sin^2(0)+sin^2(15)+sin^2(30)+sin^2(45)+sin^2(60)+sin^2(75)+sin^2(90).
Va rog sa ma ajutati :o3

Answer 1

sin^2(a) + cos^2(a) = 1
sin(pi/2 - u) = cos(u)
sin^2(0) + sin^2(90)  = 1
sin^2(15) + sin^2(75)  = 1
sin^2(30) + sin^2(60)  = 1
sinsin^2(45) = $(\sqrt{2} /2)^{2}$ = 1/2
suma totala = 7/2