To solve the equation 2sin(2x) = cosx, you should write it as _____. A. cosx(4sinx - 1) = 0 B. 2sinx + cosx = 0 C. cosx(2sinx - 1) = 0

Question

To solve the equation 2sin(2x) = cosx, you should write it as _____.	A.	cosx(4sinx - 1) = 0	B.	2sinx + cosx = 0	C.	cosx(2sinx - 1) = 0

tkhunny · Answer

$2\sin(2x) - \cos(x) = 0$

I don't see that option.  Use the sine double angle.

$2(2\sin(x)\cos(x)) - \cos(x) = 0$
$4\sin(x)\cos(x) - \cos(x) = 0$

I don't see that option.  Factor.

$\cos(x)(4\sin(x) - 1) = 0$

Now, we're talkin'!!

anonymous · Answer

How do you solve these kinds of problems?

tkhunny · Answer

Thought and creativity?  Find SOME way to factor.