Incircle of ABC touches the sides AB at P, BC at Q and CA at R. If AB = 10 cm and CR = 6 cm then
the semiperimeter of ABC (in cm) is

It can be observed that

AP=AR, BP=BQ, CQ=CR since these are the tangents to the incircle from points A,B and C respectively. Perimeter = AB+BC+CA= (AP+BP)+(BQ+CQ)+(CR+AR)=(AP+AR)+(CR+CQ)+(BP+BQ)=2AP+2BP+2CR=2(AB+CR)=2(10+6)=2(16)=2(SEMIPERIMETER)

Therefore, SEMIPERIMETER= 2(16)/2=16 units