Subject :IMO Class : Class 10
In the given figure (not drawn to scale), OABC is a quadrilateral with ABC on horizontal ground and O is vertically above A. M is the mid-point of BC. If ∠BAC = 90°, AB = AC = 16 cm and OA = 12 cm, calculate the length of OB.
A25 cm
B15 cm
C20 cm
D28 cm
I don't understand what we are finding. OC or OB clearly angle OAB is 180 degrees,