Prove that the points (7, 10), (-2, 5) and (3, -4) are the vertices of an isosceles right triangle.
Vertices of a quadrilateral are A (7, 10), B(-2, 5) and C(3, -4)
Using distance formula =
AB = 
= 
= 
units
BC = 
= 
= 
units
AC = 
= 
= 
units
Since AB = BC
Using Pythagoras theorem
AC2 = AB2 + BC2
212 = 106 + 106
212 = 212
Therefore vertices are of right isosceles triangle.
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