SOLUTION: use an identity to solve the equation: six^2x -cosx+3=0

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Question 358876: use an identity to solve the equation: six^2x -cosx+3=0
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
+%28sinx%29%5E2+-+cosx%2B3=0,
1-%28cosx%29%5E2+-+cosx%2B3=0,after using the Pythagorean identity.
-%28cosx%29%5E2+-cosx%2B4=0,
%28cosx%29%5E2+%2Bcosx-4=0.
Applying the quadratic formula,
cosx+=+%28-1+%2B-+sqrt%28+1%5E2-4%2A1%2A-4+%29%29%2F%282%2A1%29,
cosx+=+%28-1%2B-sqrt%2817%29%29%2F2.
However, these values are greater than 1, and also less than -1. Therefore the trigonometric equation does not have roots.