document.write( "Question 965646: Given cosθ=\"1%2F4\" and 270° < θ < 360° degrees, find sin2θ exactly. \n" ); document.write( "
Algebra.Com's Answer #590219 by Edwin McCravy(20064)\"\" \"About 
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Given cosθ=\"1%2F4\" and 270° < θ < 360° degrees, find sin2θ exactly
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document.write( "Since \"cos%28theta%29=x%2Fr\", we draw x = numerator of \"1%2F4\", which is 1,\r\n" );
document.write( "and r = the denominator of \"1%2F4\", which is 4. Since 270° < θ < 360°, θ is in\r\n" );
document.write( "the 4th quadrant, we draw angle θ in the 4th quadrant like this, with the\r\n" );
document.write( "red arc indicating angle θ:\r\n" );
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document.write( "\"sin%282theta%29=2sin%28theta%29cos%28theta%29\"\r\n" );
document.write( "\"sin%282theta%29=2%28y%2Fr%29%28x%2Fr%29\"\r\n" );
document.write( "\"sin%282theta%29=2%28-sqrt%2815%29%2F4%29%281%2F4%29\"\r\n" );
document.write( "\"sin%282theta%29=-2sqrt%2815%29%2F16\"\r\n" );
document.write( "\"sin%282theta%29=-sqrt%2815%29%2F8\"\r\n" );
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document.write( "Edwin
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