A, B and D are points on the circumference of a circle, centre O. BOD is a diameter of the circle.
BC and AC are tangents to the circle.
Angle OCB =34.
Work out the size of angle DOA.

Determine whether the set of whole numbers is closed under addition. explain why the set is or is not closed. give an example.

For the rule of 78, for a 12-month period, the last term in the sequence is 12 and the series sums to 78. for an 10 month period, the last term is and the series sum is . for a 15 month period, the last term is and the series sum is . for a 20 month period, the last term is and the series sum is

The graph shown is the graph of which function?