GCSE examiners have been accused of being "masochists" for setting a maths question that students claimed was "impossible". Thousands of 16-year-olds across England sat the exam last week but found ...

AO and OC are both radii of the circle. Length AO = Length OC Draw the line OB. It creates two triangles OCB and OAB. These share the length OB.

It is important to remember other angles rules, such as angles on a straight line add up to 180°, and to recognise angles in parallel lines. Make sure you are confident in applying Pythagoras’ theorem ...