Angle rules (parallel lines) and circle theorems

Question 1

name as many circle theorems as you can

Answer 1

• angle in a semicircle is always a right angle
• a tangent to a circle forms a right angle with the radius at that point
• a triangle formed by 2 radii is isosceles
• a diameter bisects a chord at right angles (any chord which is a ppd bisector of another chord = diameter)
• an angle subtended at the centre of a circle is double the angle subtended at the circumference by the same arc
• angles subtended by an arc in the same segment are equal
• opposite angles in a cyclic quadrilateral sum to 180
• 2 tangents to a circle, drawn from a single point outside the circle, are the same length and create congruent right angled triangles
• the angle between a tangent and chord is equal to the angle subtended from ends of the chord in an alternate segment

Question 2

what is a line that crosses a pair of parallel lines called?

Answer 2

a transsversal

Question 3

what are corresponding angles?

Answer 3

• equal
• F shape

Question 4

what are complimentary angles?

Answer 4

• sum to 180
• C shape

Question 5

what are alternate angles?

Answer 5

• equal
• Z shape

Question 6

what are vertically opposite angles?

Answer 6

• equal

Question 7

what are the proofs of congruency for triangles?

Answer 7

• RHS
• SSS
• SAS
• ASA
• AAS