Make a rectangular coordinate system with a as the origin and AB as the x axis.

The coordinates of p and q are P(3t, 0) Q( 10-t, √ 12).

PQ=√(3t- 10+t) of the distance formula between two points? +(0-√ 12)?

Finishing PQ? =(4t- 10)？ + 12

If two circles are circumscribed, PQ=r+r=2+2=4.

T=2 or t=3 is obtained by simultaneous solution of two formulas.

T