If C1:x2+y2−20x+64=0 and C2:x2+y2+30x+144=0. Then the length of the shortest line segment PQ which touches C1 at P and to C2 at Q is ?
C1:x2+y2−20x+64=0
⟹(x−10)2+y2=62
C1=(10,0),r1=6
C2:x2+y2+30x+144=0
⟹(x+15)2+y2=92
C2=(−15,0),r2=9
Shortest distance = C1C2–r1−r2
⟹25–6–9=25–15=10