Question

3sin^2x+5cos^2x=4 помогите

Answer 1

3Sin²x + 5Cos²x = 4
3Sin²x + 3Cos²x + 2Cos²x = 4
3(Sin²x + Cos²x) + 2Cos²x = 4
3 + 2Cos²x = 4
2Cos²x = 1
$Cos ^{2}x= \frac{1}{2}\\\\ \frac{1+Cos2x}{2}= \frac{1}{2}\\\\1+Cos2x=1\\\\Cos2x=0\\\\2x= \frac{ \pi }{2}+ \pi n\\\\x= \frac{ \pi }{4}+ \frac{ \pi n}{2} ,n$∈z