Question

The radii of 2 concentric circles are 15 cm and 13 cm. A line ABCD cuts outer circle at A and D and inner circle at B and C. If BC 10 cm, find the length of AB. ​

Answer 1

Answer:

Given:OP=17cm and OR=OQ=10cm

QR=12cm

To find PQ

Drop OM perpendicular to QR

Since perpendicular from center to chord bisects the chord.

MQ=6cm

In △OMQ,MQ=6cm,OQ=10cm

Using Pythagoras theorem,

OM=  

100−36

​

=  

64

​

=8cm

In △OMP,OM=8cm,OP=17cm

Using Pythagoras theorem,

PM=  

289−64

​

=  

225

​

=15cm

Clearly, PQ=PM−QN=15−6=9cm

Step-by-step explanation: