Question

Which of the following points lie in the interior of the circle whose radius 10 and whose center is at the origin?
A) (-9,4)
B) (5,-9)
C) (0,-10)
D) (10,-1)
E) (-6,8)

Answer 1

Equation of circle => x^2 + y^2 = 100

Now put the points you are given in the equation.

If x^2 + y^2 < 100, the point is inside the circle.
Else
If x^2 + y^2> 100, the point is outside the circle.
Else
The point is on the circle, which is essentially when x^2 + y^2 = 100.

Understood? :)

Answer 2

Thanks!