document.write( "Question 993428: Show that the points A (-1,-1),B (-3,4), and C (4,1) are the vertices of a right triangle. \n" ); document.write( "
Algebra.Com's Answer #612706 by Cromlix(4381)\"\" \"About 
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Hi there,
\n" ); document.write( "Using gradients:-
\n" ); document.write( "AB = y2 - y1/x2 - x1
\n" ); document.write( "AB = 4-(-1)/-3-(-1)
\n" ); document.write( "AB = 5/-2
\n" ); document.write( "AB = -5/2
\n" ); document.write( "BC = y2 - y1/x2 - x1
\n" ); document.write( "BC = 1 - 4/4-(-3)
\n" ); document.write( "BC = -3/7
\n" ); document.write( "AC = y2 - y1/x2 - x1
\n" ); document.write( "AC = 1 -(-1)/4-(-1)
\n" ); document.write( "AC = 2/5
\n" ); document.write( "Lines that are perpendicular
\n" ); document.write( "to one another have gradients
\n" ); document.write( "that multiply together to give -1
\n" ); document.write( "Side AB and side AC's gradients
\n" ); document.write( "multiply together to give -1
\n" ); document.write( "-5/2 x 2/5 = -1
\n" ); document.write( "Right angle is at A
\n" ); document.write( "Hope this helps :-) \n" ); document.write( "
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