Sine, cosine, tangent

article
Why stop at three by one

Beautiful mathematics. Two 18 year old students gave eight different proofs of one result then generalised it from the 3 by 1 case to the n by 1 case and proved the general result.
article
Muggles, Logo and gradients

Logo helps us to understand gradients of lines and why Muggles Magic is not magic but mathematics. See the problem Muggles magic.
article
The history of trigonometry- part 1

The first of three articles on the History of Trigonometry. This takes us from the Egyptians to early work on trigonometry in China.
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History of trigonometry - part 2

The second of three articles on the History of Trigonometry.
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History of trigonometry - part 3

The third of three articles on the History of Trigonometry.
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Making maths: clinometer

You can use a clinometer to measure the height of tall things that you can't possibly reach to the top of, Make a clinometer and use it to help you estimate the heights of tall objects.
interactivity
Round and round a circle

Age

14 to 16

Challenge level

Can you explain what is happening and account for the values being displayed?
problem
Coke machine

Age

14 to 16

Challenge level

The coke machine in college takes 50 pence pieces. It also takes a certain foreign coin of traditional design...
problem
Strange rectangle 2

Age

16 to 18

Challenge level

Find the exact values of some trig. ratios from this rectangle in which a cyclic quadrilateral cuts off four right angled triangles.
problem
30-60-90 polypuzzle

Age

16 to 18

Challenge level

Re-arrange the pieces of the puzzle to form a rectangle and then to form an equilateral triangle. Calculate the angles and lengths.