Does the point (–2.5, 3.5) lie inside, outside or on the circle x2 + y2 = 25?
The equation of the given circle is x2 +y2 = 25.
x2 +y2 = 25
(x– 0)2 +(y – 0)2 = 52, which is of the form (x – h)2+ (y – k)2 =r2,
Where, h=0, k=0 and r=5.
Distance between point (-2.5, 3.5) and the centre (0,0)
= 
=
=
=4.3 (approx.) <5
Since, the distance between point (-2.5, -3.5) and the centre (0, 0) of the circle is less than the radius of the circle, point (-2.5, -3.5) lies inside the circle.
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