document.write( "Question 400653: Prove (SinA+CosA)^2=1+Sin2A\r
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Algebra.Com's Answer #283608 by richard1234(7193) $\"\"$ $\"About$

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Expanding the left side, we get\r
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\n" ); document.write( "\n" ); document.write( " $\"sin%5E2%28a%29+%2B+2sin%28a%29cos%28a%29+%2B+cos%5E2%28a%29\"$ Since $\"sin%5E2%28a%29+%2B+cos%5E2%28a%29+=+1\"$ , and $\"2sin%28a%29cos%28a%29+=+sin%282a%29\"$ , the expression is equivalent to\r
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\n" ); document.write( "\n" ); document.write( " $\"1+%2B+sin%282a%29\"$ , and we're done. \n" ); document.write( "

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