Question 770143: Solution for cos4x=cos2x
Found 2 solutions by tommyt3rd, Alan3354:
Answer by tommyt3rd(5050)   (Show Source):
Answer by Alan3354(69443)  (Show Source):
You can put this solution on YOUR website! Solution for cos4x=cos2x
------------
cos(2A) = 2cos^2(A) - 1 double angle formula
---
cos4x=cos2x
2cos^2(2x) - 1 = cos(2x)
2cos^2(2x) - cos(2x) - 1 = 0
(2cos + 1)*(cos - 1) = 0
cos(2x) = 1
2x = 0 + 2n*pi, n = 0,1,2,3...
x = 0 + n*pi, n = 0,1,2,3...
-----------
cos(2x) = -1/2
2x = 2pi/3, 4pi/3 + 2n*pi, n = 0,1,2,3...
x = pi/3, 2pi/3 + n*pi, n = 0,1,2,3...
|
|
|
