# Equation of a Circle Worksheet

## Instructions

## Question 1

Set the sliders as follows: a = 0 b = 0 r = 1 Can you write down the distance from the centre of the circle to the circumference and hence write down an equation for the circle?

## Question 2

The point (x, y) is a point that can move anywhere on the circumference of the circle. Set the sliders as follows: a = 3 b = 0 r = 2 Can you write down the distance from the centre of the circle to the circumference and hence write down an equation for the circle?

## Question 3

Can you manipulate the sliders so that you draw a circle that: Has a centre (-3, 1) Has the y axis as a tangent What is the equation of your circle?

## Question 4

If the circle had a centre (-1, 1) and passed through the points (0, 3), (1, 0) and (-3, 0), what would the equation of the circle be?

## Question 5

If a circle has equation (a, b) and radius r, what is the equation of the circle?