Maths - Circle Theorems
Pearson Edexcel Mathematics 2022
Chords and radii
What is always true about two radii and a chord in a circle?
They always make an isosceles triangle.
What is always true about the perpendicular bisector of a chord in a circle?
It always passes through the centre of the circle.
Angles subtended by arcs
What is true about angles created from the same arc (think slice of pie)?
What is true about angles created from the same arc (think slice of pie)?They are equal.
What is true about angle C, the angles formed by drawing lines from the ends of a diameter to the circumference?
What is true about angle C, the angles formed by drawing lines from the ends of a diameter to the circumference?It is always $90^\circ$.
Tangents
What is true about the angle that a tangent makes with the circumference of a circle?
What is true about the angle that a tangent makes with the circumference of a circle?It is always $90^\circ$.
What is always true about the length to the meeting point of two tangents?
What is always true about the length to the meeting point of two tangents?It is always equal.
Angle at the centre, alternate segment and cyclic quadrilaterals
What is always true about the angle at the centre in relation to the angle at the diameter?
What is always true about the angle at the centre in relation to the angle at the diameter?The angle at the centre is twice the one at the circumference.
What’s always true about the angle either side of the triangle?
What’s always true about the angle either side of the triangle?It’s always equal to the angle opposite.
What’s true about opposite angles in a cyclic quadrilateral?
What’s true about opposite angles in a cyclic quadrilateral?They always add up to $180^\circ$.