document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1117399>Question 1117399</A>: <I><SPAN STYLE=\"word-break: break-all;\"> P is any point inside a rectangle. Lines are drawn from P to the four vertices of the rectangle. If the areas are named A1, A2, A3, and A4, prove that A1+A3 equals half the rectangle. </SPAN>\n" );
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document.write( "The bases of triangles A1 and A3 are two of the parallel sides of the rectangle; call it the length.<br><BR>\n" );
document.write( "The two altitudes of triangles A1 and A3 together are then the width of the rectangle.<br><BR>\n" );
document.write( "Then the sum of the areas of A1 and A3, using the standard formula for the area of a triangle, is one-half the length of the rectangle times the width of the rectangle.<br><BR>\n" );
document.write( "But the area of the rectangle is length times width; therefore the sum of the areas of A1 and A3 is half the area of the rectangle. </SPAN>\n" );
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