Question

O and O' are the centres of circle of radii 20 cm and 37 cm. AB = 24 cm. What is the distance OO'?

• A. 51 cm
• B. 45 cm
• C. 35 cm
• D. 48 cm

Answer 1

The correct option is A 51 cm

AB = 24cm
$\therefore$ AC = BC = 12cm
OA = 20cm
$\therefore$ $OC=\sqrt{(OA{)}^2-(AC{)}^2}$
$=\sqrt{400-144}=16cm$
and O'A = 37 cm
$\therefore$ $O^{\prime }C=\sqrt{(O^{\prime }A{)}^2-(AC{)}^2}$
$=\sqrt{(37{)}^2-(12{)}^2}=35cm$
$\therefore$ OO' = OC + CO' = 16 + 35 = 51 cm