SOLUTION: Prove the following is an identity (5 cos E - 2 sin E)^2 + (2 cos E + 5 sin E)^2 =29

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Question 519724: Prove the following is an identity
(5 cos E - 2 sin E)^2 + (2 cos E + 5 sin E)^2 =29
Answer by Aswathy(23) About Me  (Show Source):
You can put this solution on YOUR website!
First before checking out the answer just check out the RHS side of your question.
LHS=(5cos E - 2sin E)^2 + (2cos E +5 sin E)^2
=25cos^2E-20cosEsinE + 4sin^2E + 4cos^2E +20cosEsinE+25sin^2E
=1+0+1 (using identity cos^2E+sin^2E=1)
=2
=RHS