Bunuel
A circle in the coordinate plane passes through points (-3, -2) and (1, 4). What is the smallest possible area of that circle?
A. 13π
B. 26π
C. 262√π
D. 52π
E. 64π
VERITAS PREP OFFICIAL SOLUTION:This problem requires you to leverage the definition that the longest chord in any circle is the diameter. Since the line connecting the two given points on the circle, (-3, -2) and (1, 4), is a chord, the smallest possible circle would occur if that chord were the diameter (the longest possible line).
Given that, taking the distance between (-3, -2) and (1, 4) will provide you with the diameter of that smallest possible circle. Since the horizontal difference (between x-coordinates) is 4 and the vertical difference (between y-coordinates) is 6, you can calculate the distance using Pythagorean Theorem:
4^2+6^2=c^2, so c^2=52 and \(c=\sqrt{52}=2\sqrt{13}\).
Remember that this distance is the diameter, so to find the area you'll want to cut it in half to find the radius. Therefore the radius is \(\sqrt{13}\) and \(\pi r^2=\pi (\sqrt{13})^2=13\pi\).