Question

sin2x-3cos2x=4
решите уравнение

Answer 1

$sin2x-3cos^2x=4\\2sinxcdot cosx-3cos^2x=4(sin^2x+cos^2x)\\4sin^2x-2sinxcdot cosx+7cos^2x=0; |:cos^2xne 0\\4tg^2x-2tgx+7=0\\D=4-4cdot 4cdot 7=-108 textless 0; ; net; ; net; reshenij$