Circle Theorems

Question 1

What is the isosceles rule?

Answer 1

A triangle formed by two radii is isosceles

Question 2

What is the tangent rule?

Answer 2

A tangent to a circle makes a right angle with the radius at that point.

Question 3

What is the semi circle rule?

Answer 3

The angle in a semi circle is a right angle.

Question 4

What is the bisect rule?

Answer 4

Any chord which is a perpendicular bisect or if another chord must be a diameter.

Question 5

Double subtend rule

Answer 5

The angle subtended at the centre of a circle is double the angle subtended at the circumference by the same arc.

Question 6

Subtend rule

Answer 6

Angles subtended by an arc in the same segment are equal

Question 7

Cyclic rule

Answer 7

Opposite angles in a cyclic quadrilateral sun to 180

Question 8

Tangent same line rule

Answer 8

Two tangents to a circle drawn from a single point outside the circle are the same length.

Question 9

Alternate segment rule

Answer 9

The angle between a tangent and a chord is equal to the angle subtended from the ends of the chord in the alternate segment.