Найти сумму sin^4 15^0 + cos^4 15^0

Question

Валентион

8 мая, 15:05

+1

Ответы (2)

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Эмма · Answer 1

(1-cos30) ²/4 + (1+cos30) ²/4=1/4 (1-2cos30_cos²30+1+2cos30+cos²30) =

=1/4 (2+2cos²30) = 1/2 (1+cos²30) = 1/2 (1+3/4) = 1/2*7/4=7/8

Еняша · Answer 2

= (sin^2 15^0+cos^2 15^0) ^2-1/2 * (4sin^21560*cos^2 15^0) = 1 - (1/2) sin^2 30^0=1 - (1/2) * (1/4) = 1-1/8=7/8