document.write( "Question 1204376: Find the sum
\n" ); document.write( "𝑆 = cos(𝑥 + 𝜃) + cos(2𝑥 + 3𝜃) + cos(3𝑥 + 5𝜃) + cos(4𝑥 + 7𝜃) + ⋯ + cos(40𝑥 + 79𝜃),
\n" ); document.write( "and express your answer as a product and quotient of trigonometric functions. \n" ); document.write( "

Algebra.Com's Answer #840629 by Edwin McCravy(20065) $\"\"$ $\"About$

You can put this solution on YOUR website!

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document.write( "We use this formula from \r\n" );
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document.write( "https://math.stackexchange.com/questions/17966/how-can-we-sum-up-sin-and-cos-series-when-the-angles-are-in-arithmetic-pro\r\n" );
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document.write( "We rewrite \r\n" );
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document.write( "So we substitute , , \r\n" );
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document.write( "Edwin

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