A circle touches the side PQ of a ΔAPQ at the point R and on produced sides AP and AQ at the points B and C respectively.  If the perimeter of ΔAPQ = 40 cm, then the length of AB is?

\(\frac{40}{3}\) cm 20 cm \(\frac{20}{3}\)cm 10 cm

20 cm

PR = PB, QR = QC (tangent) AB = AC (tangent) Perimeter of APQ: = AP + PQ + AQ = AP + PR + RQ + AQ = AP + PB + QC + AQ = AB + AC 40 = 2AB AB = 20 cm