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JAMB Mathematics 2021 Paper

Question : 16

Total: 40

Solution:

Concept:

The endpoints of the diameter are two points on the circle. The distance between them equals the diameter, so the radius is half of that distance.

Explanation:

Use the distance formula to find the length

PQ

Let

P(-6,1)

(x_1,y_1)

and

Q(6,6)

(x_2,y_2)

PQ = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}

Substitute the values:

PQ = \sqrt{(6 - (-6))^2 + (6 - 1)^2}

PQ = \sqrt{12^2 + 5^2} = \sqrt{144 + 25}

PQ = \sqrt{169} = 13

PQ

is the diameter, and diameter

= 2r

Therefore, radius

r = \frac{13}{2} = 6.5

units.

Answer:

A. 6.5 units

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