Originally Posted by

**wintersoltice** there are two questions.

1)

A diameter of a circle has end points at A(-5,0) and B(9,0).

The equation of the circle is (x^2) + (y^2) - 2x + 2y -3 = 0 .

If C(2,k) lies on the circle, find the value of k and hence **prove** that triangle ABC is an isosceles right-angled triangle.

[COLOR=Navy]my problems are the one highlighted in red and

my answer for k is 7 or -7. so, how can I reject k= -7 ??

i get the equation of the circle by myself, so it might be wrong, if i'm careless, that is.

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