Step-by-step explanation:
every point on the circle has the same distance from the center : r (radius).
we can see that radius right there on the x-axis : the distance of (3, 0) to (0, 0) is simply 3. that is our radius.
the distance formula is applied Pythagoras
distance² = (difference in x coordinates)² +
+ (difference in y coordinates)²
distance = sqrt( ... )
so,
(-2.5, - 2.5)
(-2.5 - 0)² + (-2.5 - 0)² = 6.25 + 6.25 = 12.5
that is not 3² = 9, so the point is NOT on the circle.
(1, 3)
(1 - 0)² + (3 - 0)² = 1 + 9 = 10
that is not 3² = 9, so the point is NOT on the circle.
(2, -sqrt(5))
(2 - 0)² + (-sqrt(5) - 0)² = 4 + 5 = 9
that IS 3² = 9, so, the point IS on the circle.
(-sqrt(3), -sqrt(7))
(-sqrt(3) - 0)² + (-sqrt(7) - 0)² = 3 + 7 = 10
that is not 3² = 9, so the point is NOT on the circle.
