document.write( "Question 1201599: Find the exact values of sin 2𝜃, cos 2𝜃, and tan 2𝜃 for the given value of 𝜃.
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Algebra.Com's Answer #836058 by ikleyn(52915)\"\" \"About 
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\n" ); document.write( "Find the exact values of sin 2a, cos 2a, and tan 2a for the given value of a.
\n" ); document.write( "cot(a) = 3/4;180° < a < 270°.
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document.write( "Since  180° < a < 270°,  angle  \"a\"  is in the 3rd quadrant, QIII.\r\n" );
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document.write( "From the definition of the cot-function, it is the ratio of the attached leg to the opposite leg.\r\n" );
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document.write( "    So, the attached leg to angle \"a\" of the right angled triangle is 3 units long horizontally, opposite to x-axis;\r\n" );
document.write( "        the opposite leg to angle \"a\" of the right angled triangle is 4 units long vertically,   opposite to y-axis.\r\n" );
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document.write( "The hypotenuse is 5 units long  ( 5 = \"sqrt%283%5E2%2B4%5E2%29\" = \"sqrt%2825%29\" ).\r\n" );
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document.write( "Hence, sin(a) = \"-4%2F5\";  cos(a) = \"-3%2F5%29\".  The signs are  \"-\",  because we are in QIII.\r\n" );
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document.write( "Therefore\r\n" );
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document.write( "    sin(2a) = 2*sin(a)*cos(a) = \"2%2A%28-4%2F5%29%2A%28-3%2F5%29\" = \"24%2F25\".\r\n" );
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document.write( "    cos(2a) = \"cos%5E2%28a%29-sin%5E2%28a%29\" = \"%28-3%2F5%29%5E2+-+%28-4%2F5%29%5E2\" = \"9%2F25+-+16%2F25\" = \"-7%2F25\".\r\n" );
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document.write( "By the way, it means that angle \"2a\" is in QII.\r\n" );
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document.write( "Next,  tan(2a) = \"sin%282a%29%2Fcos%282a%29\" = \"%28%2824%2F25%29%29%2F%28-7%2F25%29%29\" = \"-24%2F7\".\r\n" );
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