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If the radii of two circles be 6 cm and 3 cm and the length of the transverse common tangent be 8 cm, then the distance between the two centres is
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- √145cm
- √140cm
- √150cm
- √135cm
- √145cm
Correct Option: A
On the basis of question we draw a figure of two circles with centres X and Y and the length of the transverse common tangent be 8 cm , 
Here , r1 = 6 cm , r2 = 3 cm
Length of transverse tangent = √XY² - (r1 +r2)²
⇒ 8 = √XY² - 9²
⇒ 64 = XY² – 81
⇒ XY² = 64 + 81 = 145
⇒ XY = 145 cm
