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Geometry - January 08, 2004

The GMAT Sample Math question for the day is from the topic Geometry.

Question
What is the radius of the circum circle of the triangle whose sides are 5, 12 and 13 units respectively?

A. 2 units
B. 12 units
C. 6.5 units
D. 6 units
E. 7.5 units

The correct choice is (C) and the correct answer is 6.5 units.

Explanatory Answer
The triangle given is a right angled triangle as its sides are 5, 12 and 13 which is one of the Pythagorean triplets.

Note:
In a right angled triangle, the circum radius is equal to the median to the hypotenuse and is half the hypotenuse.

As the given triangle is a right angled triangle, its circum radius = 0.5 * hypotenuse = 0.5*13 = 6.5 units.

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