Предмет: Алгебра, автор: Skimi21

Скажите есть ли у меня в этих вычислениях ошибка и если есть то какая
sin^2x-корень из 3 sin x cos x = 1
sin^2x -корень из 3× sin x cos x - 1 = 0
sin^2x -корень из 3× sin x cos x - 1×(sin^2x+cos^2x) = 0
-cos^2x -корень из 3× sinx cosx = 0
Делю выражение на cos^2x и получаю
-1 - корень из 3× tgx=0
Корень из 3× tg x = -1
tgx = -1/корень из 3
x = -arctg корень из 3 / 3 +pi k
k принадлежит Z

Ответы

Автор ответа: NNNLLL54
0

Ошибка в том, что не вынесли за скобки общий множитель и потеряли один корень.

sin^2x-\sqrt3\cdot sinx\, cosx=1\\\\sin^2x-\sqrt3\cdot sinx\, cosx=sin^2x+cos^2x\\\\cos^2x+\sqrt3\cdot sinx\, cosx=0\\\\cosx\cdot (cosx+\sqrt3\cdot sinx)=0\\\\a)\; \; cosx=0\; ,\; \; x=\frac{\pi }{2}+\pi n\; ,\; n\in Z\\\\b)\; \; cosx+\sqrt3\cdot sinx=0\; |:cosx\ne 0\\\\1+\sqrt3\cdot tgx=0\; \; ,\; \; tgx=-\frac{1}{\sqrt3}\; \; ,\; \; tgx=-\frac{\sqrt3}{3}\\\\x=-arctg\frac{\sqrt3}{3}+\pi k\; ,\; k\in Z\\\\x=-\frac{\pi}{6}+\pi k\; ,\; k\in Z\\\\Otvet:\; \; x=\frac{\pi }{2}+\pi n\; \; ,\; \; x=-\frac{\pi}{6}+\pi k\; \; ,\; n,k\in Z\; .

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