SOLUTION: How many solutions does {{{cos(pi/5)(x+2)=-1}}} has over the interval 0&#8804;x<20?

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Question 1118353: How many solutions does cos%28pi%2F5%29%28x%2B2%29=-1 has over the interval 0≤x<20?
Answer by htmentor(1343) About Me  (Show Source):
You can put this solution on YOUR website!
cos%28%28pi%2F5%29%28x%2B2%29%29=-1 has solutions n%2Api, n odd
Solve for x:
%28%28pi%2F5%29%28x%2B2%29%29=n%2Api+-%3E+x%2B2+=+5n+-%3E+x+=+5n+-+2
On the interval 0≤x<20 the solutions are x = 3 (n=1) and x = 13 (n=3)