Given that ABCD is a square, M is the mid point of AD and CP is
perpendicular to MB with P on MB, prove DP = DC.
Plex lets you specify a mapping between points and their images.
Then you can draw and see the transformed image.
Two tangents are drawn to the other circle from the centres of a
pair of circles. What can you say about the chords cut off by these
tangents. Be patient - this problem may be slow to load.
I noticed this about streamers that have rotation symmetry : if
there was one centre of rotation there always seems to be a second
centre that also worked. Can you find a design that has only. . . .
Some local pupils lost a geometric opportunity recently as they surveyed the cars in the car park. Did you know that car tyres, and the wheels that they on, are a rich source of geometry?
A gallery of beautiful photos of cast ironwork friezes in Australia with a mathematical discussion of the classification of frieze patterns.
This resources contains a series of interactivities designed to
support work on transformations at Key Stage 4.
Proofs that there are only seven frieze patterns involve complicated group theory. The symmetries of a cylinder provide an easier approach.
A design is repeated endlessly along a line - rather like a stream
of paper coming off a roll. Make a strip that matches itself after
rotation, or after reflection
Charlie likes tablecloths that use as many colours as possible, but insists that his tablecloths have some symmetry. Can you work out how many colours he needs for different tablecloth designs?
When a strip has vertical symmetry there always seems to be a
second place where a mirror line could go. Perhaps you can find a
design that has only one mirror line across it. Or, if you thought
that. . . .
Consider a watch face which has identical hands and identical marks
for the hours. It is opposite to a mirror. When is the time as read
direct and in the mirror exactly the same between 6 and 7?
Investigate what happens to the equations of different lines when
you reflect them in one of the axes. Try to predict what will
happen. Explain your findings.
Does changing the order of transformations always/sometimes/never
produce the same transformation?
How many different transformations can you find made up from
combinations of R, S and their inverses? Can you be sure that you
have found them all?
I took the graph y=4x+7 and performed four transformations. Can you
find the order in which I could have carried out the
A challenging activity focusing on finding all possible ways of stacking rods.
How will you decide which way of flipping over and/or turning the grid will give you the highest total?
Numbers arranged in a square but some exceptional spatial awareness probably needed.
Patterns that repeat in a line are strangely interesting. How many types are there and how do you tell one type from another?
The centre of the larger circle is at the midpoint of one side of an equilateral triangle and the circle touches the other two sides of the triangle. A smaller circle touches the larger circle and. . . .
This article describes the scope for practical exploration of tessellations both in and out of the classroom. It seems a golden opportunity to link art with maths, allowing the creative side of your. . . .
See the effects of some combined transformations on a shape. Can
you describe what the individual transformations do?
How many different symmetrical shapes can you make by shading triangles or squares?
Sort the frieze patterns into seven pairs according to the way in
which the motif is repeated.
In how many ways can you fit all three pieces together to make
shapes with line symmetry?
Explore the effect of reflecting in two intersecting mirror lines.
In a snooker game the brown ball was on the lip of the pocket but
it could not be hit directly as the black ball was in the way. How
could it be potted by playing the white ball off a cushion?
This article for teachers suggests ideas for activities built around 10 and 2010.
A moveable screen slides along a mirrored corridor towards a
centrally placed light source. A ray of light from that source is
directed towards a wall of the corridor, which it strikes at 45
degrees. . . .
Why not challenge a friend to play this transformation game?
A fire-fighter needs to fill a bucket of water from the river and
take it to a fire. What is the best point on the river bank for the
fire-fighter to fill the bucket ?.
What angle is needed for a ball to do a circuit of the billiard
table and then pass through its original position?
Explore the effect of reflecting in two parallel mirror lines.
Can you explain why it is impossible to construct this triangle?