document.write( "Question 1010813: Express cos 90- cos 50 as a product containing only sines and/or cosines \n" ); document.write( "
Algebra.Com's Answer #626286 by ikleyn(52797)\"\" \"About 
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\n" ); document.write( "Express cos(90°)- cos(50°) as a product containing only sines and/or cosines
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\n" ); document.write( "\n" ); document.write( "Use this formula of Trigonometry\r
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\n" ); document.write( "\n" ); document.write( "(see the lesson Addition and subtraction of trigonometric functions in this site).\r
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\n" ); document.write( "\n" ); document.write( "When you apply it, you will get\r
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\n" ); document.write( "\n" ); document.write( "cos(90°)- cos(50°) = -2*sin((140°)/2)*sin((40°)/2) = -2*sin(70°)*sin(20°).\r
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