document.write( "Question 169678This question is from textbook Geometry for enjoyment and challegne
\n" ); document.write( ": The measure of one angle of a parallelogram is 40 more than 3 times another. Find the measure of each angle. \n" ); document.write( "
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in a parallelogram, the opposite angles are equal to each other.
\n" ); document.write( "the sum of the angles in a parallelogram is 360.
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\n" ); document.write( "if the parallelogram is labeled ABCD, then angle A is equal to angle C because they are opposite each other, and angle B is equal to angle D because they are opposite to each other.
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\n" ); document.write( "the labeling of the parallelogram would be:
\n" ); document.write( "A is lower left corner
\n" ); document.write( "B is upper left corner
\n" ); document.write( "C is upper right corner
\n" ); document.write( "D is lower right corner
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\n" ); document.write( "assume A and C are the smaller angles.
\n" ); document.write( "assume B and D are the larger angles.
\n" ); document.write( "the parallelogram will be tilting to the right so that corner B is to the right of corner A.
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\n" ); document.write( "problem states that the larger angle is 3 times the smaller angle plus 40 degrees.
\n" ); document.write( "since B is the larger angle and A is the smaller angle, that means that:
\n" ); document.write( "B = 3*A + 40
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\n" ); document.write( "since the sum of the angles in a parallelogram = 360 degrees then angle A + B + C + D = 360.
\n" ); document.write( "since angle A = angle C, and angle B = angle D, this can be rewritten as 2*A + 2*B = 360 degrees by substituting A for C and B for D.
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\n" ); document.write( "equation you start out with is:
\n" ); document.write( "2*A + 2*B = 360
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\n" ); document.write( "you know that B = 3*A + 40 so you can substitute in equation.
\n" ); document.write( "2*A + 2*B = 360 becomes:
\n" ); document.write( "2*A + 2*(3*A+40) = 360
\n" ); document.write( "simplify:
\n" ); document.write( "2*A + 2*3*A + 2*40 = 360
\n" ); document.write( "2*A + 6*A + 80 = 360
\n" ); document.write( "8*A + 80 = 360
\n" ); document.write( "subtract 80 from both sides of equation:
\n" ); document.write( "8*A = 360 - 80
\n" ); document.write( "8*A = 280
\n" ); document.write( "divide both sides of equation by 8:
\n" ); document.write( "A = 280 / 8
\n" ); document.write( "A = 35
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\n" ); document.write( "angle A is 35 degrees.
\n" ); document.write( "angle B is 3 * 35 + 40
\n" ); document.write( "angle B is 145 degrees.
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\n" ); document.write( "angle A and angle B = 180 degrees.
\n" ); document.write( "2 * angle A and 2 * angle B = 360 degrees.
\n" ); document.write( "this checks out with the sum of the angles of a parallelogram so the angles are good.
\n" ); document.write( "answer is:
\n" ); document.write( "smaller angle is 35 degrees.
\n" ); document.write( "larger angle is 145 degrees.
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