P(-6, 1) and Q(6, 6) are the two ends of the diameter of a given circle. Calculate the radius.
A
6.5 units
B
13.0 units
C
3.5 units
D
7.0 units
Verified Correct Answer: A.
Step-by-Step Mathematical Solution
PQ\(^2\) = (x2 - x1)\(^2\) + (y2 - y1)\(^2\)
= 12\(^2\) + 5\(^2\)
= 144 + 25
= 169
PQ = \sqrt169 = 13
But PQ = diameter = 2r, r = PQ/2 = 6.5 units
Source: WAEC / JAMB / NECO Classroom Archive (Record #60681)