Q.6.

In the above right sided figure, if OA = 5 cm, AB = 8 cm and OD is perpendicular to AB, then find CD.

CD = 2cm

..

Given -OA = 5 cm  and AC = 4 cm . OD is perpendicular to AB
To find - CD
in right agled triangle OAC
(OA)^2 - (AC)^2=(OC)^2
=>(5)^2 - (4)^2=(OC)^2
=>25-16=(OC)^2
=>9=(OC)^2
=>root over of 9 = 3cm =OC
As AO= OD=5cm      (both are radius )
OD =OC +CD
=>5cm = 3cm +OD
=>5cm -3cm =OD
=>OD = 2cm