Q.

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 AP=xm.

Based on the above information, answer the question:

Q.   Find the length PC in terms of x and hence find the value of x


Ans.

(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,

AC2=AB2+BC2

⇒AC2=72+152=49+225=274

⇒AC=16.55

⇒AP+PC=16.55

⇒x+8+x=16.55

⇒2x=8.55

⇒x=4.275~4.28 m