Question

Ncert book class 9 , ex 10.4 ,Q no 5

Answer 1

Answer:

Step-by-step explanation:

Let Reshma, Salma and Mandip takes the position C, A and B on the circle. Since AB = AC

The centre lies on the bisector of BAC.

Let M be the point of intersection of BC and OA.

Again, since AB = AC and AM bisects

CAB.

AM CB and M is the mid-point of CB.

Let OM =  then MA =

From right angled triangle OMB,

OB2 = OM2 + MB2

52 =  + MB2 ……….(i)

Again, in right angled triangle AMB,

AB2 = AM2 + MB2

62 =  + MB2 ……….(ii)

Equating the value of MB2 from eq. (i) and (ii),

Hence, from eq. (i),

MB2 =  =

=  =

MB =  = 4.8 cm

BC = 2MB = 2 x 4.8 = 9.6 cm