CAT 2019 Shift 2 Paper

Question : 72 of 100

Marks: +1, -0

Two circles, each of radius 4 cm, touch externally. Each of these two circles is touched externally by a third circle. If these three circles have a common tangent, then the radius of the third circle, in cm, is

$π/3$
1
$1/√2$
$√2$

Validate

Solution:

Refer to the figure

{SO}=4- {r}

Applying Pythagoras theorem in triangle POS, we get

(4+r)^{2}=4^{2}+(4-r)^{2}

⇒ 4 × 4 × r=16

⇒ r=1

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