3. 
In the diagram, the circle has
centre O and radius 6 cm. AOC and AED are


secants of the circle where B,
C, D and E are points on the circumference of the 

circle. Given that AC =
16 cm, AD = 14 cm, and , 

 
4. 
In the diagram, the tangent at B meets AD produced
at C. By using similar triangles,


prove that


Hence, show that 
