document.write( "Question 1014959: Find the exact value of tan (a + b) if cos a = -3/5, sin b = 5/13, 90° < a < 180°, and 90° < b < 180°. Do not round.\r
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Algebra.Com's Answer #631286 by ikleyn(52803) $\"\"$ $\"About$

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document.write( "1.  Use the addition formula for tangent:  tan(a + b) = \r\n" );
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document.write( "    (see the lesson Addition and subtraction formulas in this site).\r\n" );
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document.write( "2.  sin(a) =  =  = . . . = .\r\n" );
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document.write( "     Notice that the sign of the square root is chosen accordingly with the location of the angle \"a\" in the Quadrant 2.\r\n" );
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document.write( "3.  cos(b) = - = - = . . .  = .\r\n" );
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document.write( "     Notice that the sign of the square root is chosen accordingly with the location of the angle \"b\" in the Quadrant 2.\r\n" );
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document.write( "4.  Now,  tan(a) =  =  :  =    and\r\n" );
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document.write( "          tan(b) =  =  :  = .\r\n" );
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document.write( "5.  Finally,  tan(a+b) =  =  =  =  = .\r\n" );
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