BTGmoderatorLU wrote:Source: Veritas Prep
Which of the following is NOT a point on the circle of radius 5 and center O as graphed above?
A. (-1, 2)
B. (8, -1)
C. (0, -5)
D. (6, 3)
E. (7, -6)
The OA is
E.
Distance formula:
Note that distance between two points whose coordinates are (x, y) and (a, b) is given by
= √[(x - a)^2 + (y - b)^2]
The point whose coordinates are (x, y) is on the circle and the point whose coordinates are (a, b) is the center of the circle, thus, a = 3 and b = - 1.
Thus, Radius = √[(x - a)^2 + (y - b)^2] = √[(x - 3)^2 + (y + 1)^2]
5 = √[(x - 3)^2 + (y + 1)^2]
25 = (x - 3)^2 + (y + 1)^2
You may lug-in option values and check which one fits. You'll find that option E: (7, -6) is NOT on the circle.
Let's see:
Option E: (7, -6)
(7 - 3)^2 + (-6 + 1)^2 = 16 + 25 = 41 ≠25.
The correct answer:
E
Hope this helps!
-Jay
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