1. 
In the diagram, A, B, C and D are points on the circumference of a circle with 

centre O. AB is a diameter of the circle and .
Find 



2. 
In the diagram, the points A,
B, C and D lie on the circumference of a circle with 

centre
O. TB is a tangent to the circle and BD is a
diameter of the circle. Given 

that and . Find 
