SOLUTION: Solve cos2x=-cosx for the interval 0 ≤ x < 2pi.

SOLUTION: Solve cos2x=-cosx for the interval 0 ≤ x < 2pi.

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Question 1138005: Solve cos2x=-cosx for the interval 0 ≤ x < 2pi.
Answer by MathLover1(20849) (Show Source): You can put this solution on YOUR website!

for the interval
..........use the following identity :

.......let

solutions:
if =>
if=>

since , we have
or

if , and , then
if , and, than ,

combine all solutions: , ,

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