# Trigonometric functions and graphs

**16**NRICH Mathematical resources connected to

**Trigonometric functions and graphs**

problem

### Trig-trig

Explore the properties of combinations of trig functions in this open investigation.

problem

### Back fitter

10 graphs of experimental data are given. Can you use a spreadsheet to find algebraic graphs which match them closely, and thus discover the formulae most likely to govern the underlying processes?

problem

### Tangled Trig Graphs

Can you work out the equations of the trig graphs I used to make my pattern?

problem

### Taking trigonometry series-ly

Look at the advanced way of viewing sin and cos through their power series.

problem

### Sine and Cosine

The sine of an angle is equal to the cosine of its complement. Can
you explain why and does this rule extend beyond angles of 90
degrees?

problem

### Spherical triangles on very big spheres

Shows that Pythagoras for Spherical Triangles reduces to
Pythagoras's Theorem in the plane when the triangles are small
relative to the radius of the sphere.

problem

### What do functions do for tiny x?

Looking at small values of functions. Motivating the existence of
the Taylor expansion.