Solve sin4(theta) = cos2(theta)

**dno** · December 8th 2008, 10:07 AM

dont worry about the values im just having trouble setting it up

**TwistedOne151** · December 8th 2008, 10:23 AM

Use the double angle identity $\sin(4\theta)=2\sin(2\theta)\cos(2\theta)$ .
This gives:
$\sin(4\theta)=\cos(2\theta)$
$2\sin(2\theta)\cos(2\theta)=\cos(2\theta)$
$2\sin(2\theta)\cos(2\theta)-\cos(2\theta)=0$
$\left(2\sin(2\theta)-1\right)\cos(2\theta)=0$
You should be able to see how to solve it from there.

--Kevin C.

Thread: Solve sin4(theta) = cos2(theta)

LinkBack

Thread Tools

Display

Solve sin4(theta) = cos2(theta)

Similar Math Help Forum Discussions

Finding cos2*theta

Conditions on min poly of theta such that theta =phi^2, phi in Q(theta)

Finding the value of the angle theta in radians, knowing sec theta and cot theta

solve 8 sin (theta)-15cos(theta)=8.5

[SOLVED] Find Cos (theta), sin(theta), and tan(theta)

Search Tags