document.write( "Question 1042537: If sin θ = 2 over 7 and tan θ > 0, what is the value of cos θ?\r
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Algebra.Com's Answer #657569 by ikleyn(52873)\"\" \"About 
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\n" ); document.write( "If sin (theta) = 2 over 7 and tan (theta) > 0, what is the value of cos (theta)?\r
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document.write( "You are given \"sin%28theta%29\" = \"2%2F7\".\r\n" );
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document.write( "Then \"cos%28theta%29\" = \"sqrt%281-sin%5E2%28theta%29%29\" = \"sqrt%281-%282%2F7%29%5E2%29\" = \"sqrt%281+-+4%2F49%29\" = \"sqrt%28%2849-4%29%2F49%29\" = \"sqrt%2845%2F49%29\" = \"%283%2Asqrt%285%29%29%2F7\".\r\n" );
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document.write( "Since \"sin%28theta%29\" is positive and \"tan%28theta%29\" is positive (given !), the angle \"theta\" is in the first quadrant.\r\n" );
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document.write( "Since \"theta\" is in QI, the sign at the square root is positive.\r\n" );
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document.write( "Answer.  \"sin%28theta%29\" = \"%283%2Asqrt%285%29%29%2F7\".\r\n" );
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