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The distance between centres of two circles of radii 3 cm and 8 cm is 13 cm. If the points of contact of a direct common tangent to the circles are P and Q, then the length of the line segment PQ is :
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- 11.9 cm
- 12 cm
- 11.58 cm
- 11.5 cm
- 11.9 cm
Correct Option: B
As per the given in question , we draw a figure of two circles of radii 3 cm and 8 cm 
Given that , OO' = 13 cm
PQ = √(OO')² - (r2 - r1)²
PQ = √(13)² - (8 - 3)²
PQ = √169 - 25
PQ = √144 = 12 cm.
