Change the values of [math]a[/math], [math]b[/math] and [math]r[/math] 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?[br][br]Use the checkbox to show a triangle on the circle. Write down expressions in terms of [math]a[/math], [math]b[/math] and [math]r[/math] for the length of each side. How does this explain the equation of the circle?