Question

how solve triangle sums of class 10th

Answer 1

In triangle APQ and triangle ABC,
Angle A=angle A(common)
AP/PB=AQ/QC=1/2
triangle APQ~triangle ABC (SAS similarity)
AP/AB=PQ/BC
3/3+6=PQ/BC
3/9=PQ/BC
1/3=PQ/BC
by CM,
BC=3PQ.