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Originally Posted by Thelema cos2t+2cos^2(t/2)-2=0
I am sure you know what to do now
Originally Posted by Thelema cos2t+2cos^2(t/2)-2=0 Double angle formula: .
Substitute A = t/2: .
So your equation can be re-written as ......
Check for mistakes - but you get the idea, right?
Let .. is not possible because cos is between -1 and +1.
So we only use
Solve this for t.
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