# JST17 5. Section 2a Circles

- Author:
- Jill Stephenson, Integral Resources

- Topic:
- Circle

Change the values of , and to see different circles. Write down the centre and radius for each circle. How can you predict the centre and radius from the equation of the circle?
Use the checkbox to show a triangle on the circle. Write down expressions in terms of , and for the length of each side. How does this explain the equation of the circle?