Q24 / 58 · KVPY 2016 (SA) · Mathematics

Three circles of radii 1,2 and 3 units respectively touch each other externally in the plane. The circumradius of the triangle formed by joining the centers of the circles is

A
$1.5$
B
2
Correct answer
C
$2.5$
D
3

Solution

Formed triangle will be right angle whose sides are $3,4,5$ $\text { So. circumradius }=\frac{\text { length of hypotenuse }}{2}=2.5$

Hence, the correct answer is option: 'C'.

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