hi mate

here is your answer

We know,

AP= 3.5CM ,PC =7CM,

AQ=3CM, PQ= 6CM

So, by using CONVERSE OF BPT=>>

AP/PC = AQ/PQ = 1/2 ----(i)

So in triangle AQP and ABC=

angle QAP = angle BAC

( COMMON ANGLE)

AP/PC = AQ/PQ -------(from i)

So, traingle AQP similar to traingle ABC.

(BY SAS SIMILARITY CRITERIA)

Also, AP/PC = AQ/PQ = QP/BC = 1/2

(CPCT)

SO, QP/BC =1 /2

=> 6/BC =1/2

=> BC = 12CM

HOPE IT HELP

BE BRAINLY///