document.write( "Question 773336: Use the sum and difference identity to write the expression as the ine, cosine or tangent of an angle.
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Algebra.Com's Answer #471456 by Edwin McCravy(20060) $\"\"$ $\"About$

You can put this solution on YOUR website!
cos20degreescos30degrees-cos20degreessin30degrees
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document.write( "cos(A+B) ≡ cos(A)cos(B) - sin(A)sin(B)\r\n" );
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document.write( "Let A = 20° and B = 30°\r\n" );
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document.write( "cos(20°+30°) ≡ cos(20°)cos(30°) - sin(30°)sin(20°)\r\n" );
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document.write( "Answer: cos(50°)\r\n" );
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document.write( "[Incidentally you can type the little circle degree mark °\r\n" );
document.write( "by holding down the ALT key while you type 248 on the keypad\r\n" );
document.write( "at the far right of your keyboard. When you let up the ALT\r\n" );
document.write( "key the ° will appear on your screen.]\r\n" );
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document.write( "Edwin

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