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The Geometry of Pizza
The Geometry of Pizza
Imagine a pizza. The crust is the circle's circumference. Cut a slice from the centre? That's two radii making an angle at the centre. But what if you connect two points on the crust to another point ON the crust? That angle is always exactly HALF the centre angle. Circle theorems are about these beautiful relationships!
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Common Mistakes
X Angle at circumference = 2× angle at centre
Angle at CENTRE = 2× angle at circumference
Don't reverse the relationship!
X Adjacent angles in cyclic quad = 180°
OPPOSITE angles in cyclic quad = 180°
Must be opposite, not adjacent
Now try it yourself
Quiz · Question 1 of 18
AB is a diameter of a circle. Point C lies on the circle. What is the size of angle ACB?
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This topic in real past papers
Every real exam question we've found on circle theorems, with a full worked answer.