Copy the picture to draw this spiral. Then create your own elephant. The numbers in the centres of the squares give the radii of the quarter circles that you need to draw.
What do you notice about this sequence of numbers 1, 1, 2, 3, 5, 8, 13, 21 … ? […]
a. Draw 2 circles with equal radii, intersecting at C, so that each goes through the centre of the other.
b. Draw a third circle of the same radius with centre C.
c. Draw 4 more circles with centres on the circle centre A and passing through A.
Draw a circle and mark 24 points equally spaced around the circumference. To do this, draw a circle and mark the centre, and mark your first point on […]
Try to estimate the distance around the tree trunk at its base measured in metres.
Does this picture give you an idea how you might use the picture, with your class at school, to work out a better estimate […]
The line RS is a tangent at P to the circle centre O and radius 1 unit.
Find the lengths OQ, PQ, PS, OS, OR and RP.
If OS and OR lie on the coordinate axes, what are the coordinates […]
If the can’s diameter is 6 cm what is the can’s height?
If instead the can’s height was 10 cm what would the can’s diameter have to be?
Which of these two cans uses the least aluminium?
If you could choose any diameter which dimensions for […]
Suppose another fence is built exactly one metre longer so the path between the two fences is the same width all the way round including at the corners of the field.
How wide would this path be?
Would a mouse be able to run along it? […]
A wire belt is tied tightly around the Earth at the equator. Suppose the belt is made exactly one metre longer and held around the Earth at the equator so that it is the same distance away from the Earth everywhere. Would a mouse be able to crawl under the new belt? How do […]
The angle marked in the diagram is angle a.
Copy the diagram and find all the angles in terms of the angle a.
Find the six line segments in the diagram corresponding to sina, cosa, tana, 1/sina, 1/cosa and 1/tana.
Find the areas of […]
Describe the path (or locus) of the centre of the circle and its length.
Try this on the NRICH interactivity.