Question 984271: How many solutions does cos(4x) = .4 have? Please explain how to do this problem?
Answer by Cromlix(4381)   (Show Source):
You can put this solution on YOUR website! Hi there,
The original two solutions for
cos(4x) = 0.4
= 66.4 and 293.6 (360 - 66.4)
Because you have 4x after the cos
then 360 degrees must be added to
66.4 and 293.6 three times.
Therefore:
4x = 66.4, 293.6, 426.4, 653.6,
786.4, 1013.6, 1146.4, 1373.6.
Now to find what 'x' =
Divide each of the solutions by 4
x = 16.6, 73.4, 106.6, 163.4,
196.6, 253.4, 286.6, 343.4.
You would give these solutions
for 0 < x < 360.
Hope this helps you. :-)
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