Geogebra

1. 1
Follow these instructions below to discover some interesting theorems about circles
using Geogebra. This is a free download that you can use at home!
Make sure you copy all your work onto a PowerPoint including all the answers to the
questions posed and upload
Task A
1) Try to draw : tangent, chord, radius and diameter.
2) Also draw a triangle with the vertex at the centre of the circle. What kind of triangle
is this?
Here are some instructions how to draw a circle.
Drawing a circle

2. 2
Task B
Angles subtended from the diameter at the circumference
Drawing a line through the centre
Add another point C
Draw a ray between two point
Measure the angle
Now move your point D. What do you notice about the angle?
Angles between Tangent and Radius
Reproduce this diagram and state the theorem. Make sure you use the arrow tool to
move the points to see whether your theorem is always true.