AB is a direct common tangent of two circles of radii p and q touching each other externally. Then the value of AB2
pq
2pq
3pq
4pq
LET AB be the direct common tangent, OA = p and BI = q
Let T be any point on line AI such that OI || BT
then, BI = OT = q
AT = p - q
TB = p + q
ATB is a right angle triangle
Apply Pythagoras theorem