Solve for x and find all solutions in degrees from 0 to 360

20cos^2x+sin4x=13

I know you need to use the identity to turn cos^2x into 1-sin^2x but after I distribute I get lost. Please help me understand the question by writing out thought proccess thanks.

evanborot Nov 24, 2019

#1**0 **

https://www.mathway.com/Algebra says there is no solutions that make this equation true for real numbers.

https://www.wolframalpha.com/input/?i=20cos%5E2%28x%29%2Bsin%284x%29%3D13 Well, wolfram doesn't have specific solution and some are complex no.

Guest Nov 24, 2019

#2**-1 **

I'll try to help

\(20(1-\sin^2x)+\sin4x=13\)

\(20-20\sin^2x+\sin4x=13\)

Bring all the sines to one side and numbers to the other.

\(20\sin^2x-\sin4x=7\)

Hopefully, from there you can find it.

You are very welcome!

:P

CoolStuffYT Nov 24, 2019