Mathematics
The length of the direct common tangent to two circles of radii 12 cm and 4 cm is 15 cm. Calculate the distance between their centres.
Circles
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Answer
Let there be two circles with center A and B and radius 12 and 4 cm respectively.
From figure,
TT' is the common tangent.
DT = BT' = 4 cm.
DB = TT' = 15 cm.
In right angled triangle ADB
AD = AT - DT = 12 - 4 = 8 cm
Hence, the distance between two centres = 17 cm.
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