Q 1 :    

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 of AR in terms of x.



Given, AB = 7 m, BC = 15 m and AP = x m

Hence, AP = AR (Tangent drawn from an external point to the circle are equal in length)

 AR = x m

 



Q 2 :    

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.   Write the type of quadrilateral BQOR.



Since, AR = x m and AB = 7 m

 RB = (7 – x)m

Also, RB = BQ

(Tangents drawn from an external point to the circle)

OR = OQ (radii of circle)

ORB = OQB = 90° (Angle between radius and tangent)

Also, RBQ = 90° (angle between the walls AB and BC)

Thus, ROQ = 90°

Thus, BQOR is square.

 



Q 3 :    

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



(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