SOLUTION: Show that the points A (-1,-1),B (-3,4), and C (4,1) are the vertices of a right triangle.

Algebra ->  Coordinate-system -> SOLUTION: Show that the points A (-1,-1),B (-3,4), and C (4,1) are the vertices of a right triangle.      Log On


   



Question 993428: Show that the points A (-1,-1),B (-3,4), and C (4,1) are the vertices of a right triangle.
Answer by Cromlix(4381) About Me  (Show Source):
You can put this solution on YOUR website!
Hi there,
Using gradients:-
AB = y2 - y1/x2 - x1
AB = 4-(-1)/-3-(-1)
AB = 5/-2
AB = -5/2
BC = y2 - y1/x2 - x1
BC = 1 - 4/4-(-3)
BC = -3/7
AC = y2 - y1/x2 - x1
AC = 1 -(-1)/4-(-1)
AC = 2/5
Lines that are perpendicular
to one another have gradients
that multiply together to give -1
Side AB and side AC's gradients
multiply together to give -1
-5/2 x 2/5 = -1
Right angle is at A
Hope this helps :-)