SOLUTION: Find all values of x in the interval [0, 2π] that satisfy the equation 6 cos(x) + 3 sin(2x) = 0

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Question 1045173: Find all values of x in the interval [0, 2π] that satisfy the equation
6 cos(x) + 3 sin(2x) = 0

Answer by ikleyn(52794) About Me  (Show Source):
You can put this solution on YOUR website!
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Find all values of x in the interval [0, 2π] that satisfy the equation
6 cos(x) + 3 sin(2x) = 0
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6*cos(x) + 3*sin(2x) = 0,

Divide both sides by 3 and replace  sin(2x)  by  2*sin(x)*cos(x):  sin(2x) = 2*sin(x)*cos(x).  You will get

2*cos(x) + 2*sin(x)*cos(x) = 0.

Divide both sides by 2. You will get

cos(x) + sin(x)*cos(x) = 0.

Factorize: 

cos(x)*(1+sin(x)) = 0.

The equation deploys in two independent equations:


1)  cos(x) = 0  --->  x = pi%2F2  and/or  x = 3pi%2F2.


2)  1+sin(x) = 0  --->  sin(x) = -1  --->  x = pi.

Answer. The solutions are pi%2F2%7D%2C++%7B%7B%7Bpi  and 3pi%2F2.