A backyard is in the shape of a triangle ABC with right angle at B. AB = 7 m and BC 15 m. A circular pit was dug inside it such that it touches the walls AC, BC and AB at P, Q and R respectively such that .

Based on the above information, answer the question:
Q. Find the length PC in terms of and hence find the value of
(4.28)
Here, BC = 15 m
BQ = (7 – x)m
QC = 15 – (7 – x)
or, QC = (8 + x)m
Also, QC = PC (Tangents from an external points C to the circle)
i.e., PC = (8 + x)m
In right DABC, using Pythagoras theorem,