The midpoint of two points

Use the checkbox to see how you can find the midpoint.[br]You can move the two points.

The distance between two points

Use the checkbox to see how Pythagoras' theorem is used to find the distance between two points.[br]You can move the two points.

The gradient of a line joining two points

Use the checkbox to see how you can find the gradient of the line joining the two points.[br]You can move the two points.

Parallel lines

You can change the blue line by moving either of the green points.[br]The red line is parallel to the blue line. What do you notice about the gradients and the equations of the lines?

The form y = mx + c

Use the sliders to set the values of m and c, and then use the checkbox to see the line.[br]What is the significance of the values of m and c?
The form y = mx + c

Circles

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?

Tangent and radius

A tangent to a circle at a point is perpendicular to the radius of the circle at that point.[br]Move the point P around the circle to see that the tangent is always perpendicular to the radius.
This construction [i]demonstrates[/i] this circle theorem, but it does not [i]prove[/i] it. Try to prove the theorem.

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