Topic/Skill Definition/Tips Topic: Equation of a Circle
Example
and Tangent
1. Equation of The equation of a circle, centre (0,0),
a Circle radius r, is:
2 2 2
x + y =r
2 2
x + y =25
2. Tangent A straight line that touches a circle at
exactly one point, never entering the
circle’s interior.
A radius is perpendicular to a tangent at
the point of contact.
3. Gradient Gradient is another word for slope.
Rise Change∈ y y 2− y 1
G= = =
Run Change∈ x x 2−x 1
4. Circle A tangent is perpendicular to the radius
Theorem 5 at the point of contact.
Subject: Maths
y=5 cm(Pythagoras’ Theorem)
Mr A. Coleman Glyn School
Example
and Tangent
1. Equation of The equation of a circle, centre (0,0),
a Circle radius r, is:
2 2 2
x + y =r
2 2
x + y =25
2. Tangent A straight line that touches a circle at
exactly one point, never entering the
circle’s interior.
A radius is perpendicular to a tangent at
the point of contact.
3. Gradient Gradient is another word for slope.
Rise Change∈ y y 2− y 1
G= = =
Run Change∈ x x 2−x 1
4. Circle A tangent is perpendicular to the radius
Theorem 5 at the point of contact.
Subject: Maths
y=5 cm(Pythagoras’ Theorem)
Mr A. Coleman Glyn School
