SOLUTION: Solve: {{{sin2x=cosx}}}, {{{-2pi<=x<=pi}}}

Algebra.Com
Question 553053: Solve:
,

Found 2 solutions by Alan3354, solver91311:
Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
Solve:
,
-----------------
2sinx*cosx = cosx
2sinx*cosx - cosx 0
cos(x)*(2sin(x) - 1) = 0
cos(x) = 0
x = pi/2, -pi/2, -3pi/2
------
2sin(x) = 1
sin(x) = 1/2
x = -11pi/6, -7pi/6, pi/6, 5pi/6

Answer by solver91311(24713)   (Show Source): You can put this solution on YOUR website!


Since we can write:



Multiply by







Use the unit circle, recalling that sin of the angle is the -coordinate of the point of intersection of the terminal ray with the unit circle and find all angles where in your given interval. Note that the given interval is one and a half trips around the circle. Hint: start at and go backwards.



John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism


RELATED QUESTIONS

solve for x for: sinx - sin2x = cosx on [-pi,... (answered by Alan3354,Edwin McCravy)
Solve: sin2x = cos x ,{{{-2pi <= x <=... (answered by Alan3354)
Solve the equation algebraically for "x" where 0≤x<2π. sin2x=cosx Thank... (answered by Fombitz)
Solve {{{sin2x-cosx=0}}} given that 0 ≤ x <... (answered by greenestamps)
Solve for (0<=x<=360) sin2x-cosx=-1+2sinx... (answered by Alan3354,ikleyn)
sin2x=cosx [-pi;2pi] I don't how to explain it cause English isn't my native language but (answered by Alan3354)
Please help me solve this equation: {{{ cosx=sin2x... (answered by lwsshak3)
15. Solve for 0≤𝑥<2𝜋: cosx ∙ sinx =... (answered by greenestamps)
Solve the eq on the interval [0,2pi) : sin2x-cosx=0 I used the indetity sin2x =... (answered by solver91311,Alan3354)