# Circles

The loci of a distance from a point is a circle. It describes a complete turn and allows us to work out many different things.

Important words to do with circles include centre, radius, circumference, diameter, tangent, chord, sector, segment and Pi.

The equation of a circle is x^2 + y^2 = r^2. If we alter it slightly, we get an elipse instead.

Circles are truely fascinating and we use them every day.

## Circle Theorem

Use the circle theorems to find the angles in a circle. A list of keywords is included and some sentences with cloze procedure.

## Area of a circle

Use the Pi button on your calculator to work out the are of there circles.

## Parts of a Circle

Information sheet showing the parts of a circle.

## Circle Theorem Questions

Use your knowledge of circle theorems to calculate the missing angles.

## Find the area of the circle.

This is a difficult problem combining trigonometry, area of a circle, co-ordinates and midpoints to find the solution.

## Two Cirlces

Two circles with the centre point marked. You can use this for all kinds of things. Naming the parts of a circle, find the area and circumference to name but a few.

## Angle Problems Video

A difficult problem combining many different skills to arrive at a solution.

## A video on constructing the graph of a circle

A video about constructing a circle using the formula x^2 + y^2 = r^2 where r is the radius.

## A video going through the parts of a circle

This is a video on the parts of a circle.

## Finding the area of a circle using trigonometry

Find the area of a circle using trigonometry.

## Example of circle question

Example of a circle question with similiar type questions to follow.

## Area of Circles, Sectors and Segments

A face is given with dimensions upon it. You have to calculate the area of the skin by working out the areas of various circles, segments and sectors to find the final answer.

## Circles and Lines

Use substitution in simultaneous equations to calculate the intersect points of a straight line and circle.

## Area of Sectors

Find the area of a sector by finding the area of the fuill circle and then multiplying it by the angle at the centre of the circle divided by 360.

## Label the lines in a circle

Label the lines and areas of a circle.