In the diagram,the chord AB is perpendcular to the diameter CD,AB=70cm and CE=25cm.Find

a)the radius of the circle

b)the area of triangle AOB,where O is the centre of the circle.

http://i275.photobucket.com/albums/j...ngming/1-1.jpg

ans is:

a)37cm

b)420cm^2

i nid help on how to get the answer.