document.write( "Question 615495: Two forces act on a body at an angle of 100 degrees. The forces are 30 and 40 pounds.
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Algebra.Com's Answer #387225 by Edwin McCravy(20060)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "Here's the complete solution:\r\n" );
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document.write( "Draw a little rectangle for the body, and sticking out of the body,\r\n" );
document.write( "draw two vectors, one 3 units long for the 3 lb vector, and one 4\r\n" );
document.write( "units long for the 4 lb vector, so that the angle between the two\r\n" );
document.write( "vectors is 100°:\r\n" );
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document.write( "Next we complete the parallelogram, Through each arrowhead, draw\r\n" );
document.write( "a line parallel to the other vector.  I'll draw them in green:\r\n" );
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document.write( "The resultant of the two forces is a vector which is the diagonal of\r\n" );
document.write( "the parallelogram from the body to the point where the two green lines\r\n" );
document.write( "intersect, which I will draw in red\r\n" );
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document.write( "Two adjacent angles of a parallelogram are supplementary so the angle\r\n" );
document.write( "on the lower right is 180°-100° or 80°.\r\n" );
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document.write( "To find the magnitude of R, we use the law of cosines:\r\n" );
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document.write( "R² = a² + b² - 3·a·b·cos(phi)\r\n" );
document.write( "R² = 3² + 4² - 2(3)(4)cos(80°)\r\n" );
document.write( "R² = 20.83244374\r\n" );
document.write( " R = 4.564257194 or to the nearest tenth of a pound, \r\n" );
document.write( " R = 4.6 lb.\r\n" );
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document.write( "The angle between the 4 lb. vector and the resultant is either\r\n" );
document.write( "of the two angles labeled q below:\r\n" );
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document.write( "We'll get the q at the top right\r\n" );
document.write( "since we're working in that triangle. \r\n" );
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document.write( "\"R%2Fsin%28%2280%B0%22%29\" = \"3%2Fsin%28theta%29\"\r\n" );
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document.write( "R·sin(q) = 3·sin(80°)\r\n" );
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document.write( "sin(q) = \"3%2Asin%28%2280%B0%22%29%2FR\".\r\n" );
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document.write( "sin(q) = \"3%2Asin%28%2280%B0%22%29%2F4.564257194\".\r\n" );
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document.write( "sin(q) = 0.6472955255\r\n" );
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document.write( "Use the inverse sine function on your calculator:\r\n" );
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document.write( "q = 40.33800507°\r\n" );
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document.write( "or to the nearest degree, 40°.\r\n" );
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document.write( "Edwin
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