SOLUTION: Find all values of x in the interval [0, 2π] that satisfy the given equation. − sin 2x = √3 sin x

Algebra ->  Trigonometry-basics -> SOLUTION: Find all values of x in the interval [0, 2π] that satisfy the given equation. − sin 2x = √3 sin x      Log On


   



Question 1079106: Find all values of x in the interval [0, 2π] that satisfy the given equation.
− sin 2x = √3 sin x

Found 2 solutions by Boreal, ikleyn:
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
-2sin x*cos x=sqrt(3)*sinx
-2 cos x= sqrt(3)
cos x=-sqrt(3)/2
This occurs at 150 deg and 210 deg or (5/12 pi and 7/12 pi)
check
-sin 300=sqrt (3)*sin 150
-(-sqrt(3)/2)=sqrt(3)*1/2, check.
-sin(420)=sqrt(3)*sin (210)
- sqrt(3)/2=sqrt(3)*(-1/2), check

Answer by ikleyn(52787) About Me  (Show Source):
You can put this solution on YOUR website!
.
-sin(2x) = sqrt%283%29%2Asin%28x%29  --->

-2sin(x)*cos(x) = sqrt%283%29%2Asin%28x%29  --->

-2sin(x)*cos(x) - sqrt(3)*sin(x)}}} = 0  --->

-2sin%28x%29%2A%28cos%28x%29%2Bsqrt%283%29%2F2%29 = 0  --->


The last equation deploys in two independent equations


1.  sin(x) = 0  with the solutions  x = 0  and  x = pi.


2.  cos%28x%29+%2B+sqrt%283%29%2F2 = 0,  which is the same as  cos(x) = -sqrt%283%29%2F2,  with the solutions  x = 2pi%2F3  and x = 4pi%2F3.


Answer.  The set of solutions  is  {0, 2pi%2F3, pi, 4pi%2F3 }.




Plot y = -sin(2x) (red) and y = sqrt%283%29%2Asin%28x%29