Circle theorems are a set or rules you can use to arrive at the correct value of angles in a circle. In this article we will look at theorems 1 to 3, with the remaining being discussed in a sperarate article.

RULE 1: If you have 2 angles coming from THE SAME ARC (as shown below) –>  Angle at CENTRE = TWICE angle at CIRCUMFERENCE

RULE 2: Angles IN A SEMI CIRCLE have a 90° angle

RULE 3: Angles AT THE CIRCUMFERENCE coming from the SAME ARC are equal

Similar Shapes - Area & Volume
Trigonometric Ratios (Sine / Cosine / Tangent)