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Degree Ceremony

What does Pythagoras' Theorem tell you about these angles: 90°, (45+x)° and (45-x)° in a triangle?

After Thought

Which is larger cos(sin x) or sin(cos x) ? Does this depend on x ?

Small Steps

Two problems about infinite processes where smaller and smaller steps are taken and you have to discover what happens in the limit.


Age 16 to 18
Challenge Level
This is an investigation concerning the composition of trig functions -- it is very open-ended. You might wish to make good use of spreadsheets or other tools to get started.

Two functions $f(x)$ and $g(x)$ can be composed to create a new function $h(x) = f(g(x))$.

Explore the properties of functions which can be created by composing two trig functions: $\sin(x)$, $\cos(x)$ and $\tan(x)$ on the range $-\pi < x \leq \pi$.

Which combinations are finite, which combinations have finite numbers of turning points and which combinations have no turning points on the specified range? What are their maximum and minimum values?

Extension: Explore the properties of nested sequences of $\sin$ and $\cos$: $\sin(\sin(\sin(x)))$ and $\cos(\cos(\cos(x)))$ or see what happens when you compose other functions.