Determine whether a triangle with the given vertices is a right triangle

A(9, -3), B(-1, 1), C(-5, -9) is not a right triangle

P(2, 0), Q(-6, 10), R(-10, 4) is a right triangle

T(-2, 4), R(6, 0), I(-5, -2) is a right triangle

I just plug in the numbers into the coordinate plane and traced the dots to create triangles like the first one which it was an isosceles triangle and the other two were right triangles with angles of 90 degrees.

Hope this helped you :)

the answer is two. hope this !