Just do part 1 if you like where you will construct a golden rectangle and find an approximate value of the golden ratio by measurement.

If you want to go further there are many hints within this question to take you through it. You will find the value of f first by drawing and measurement, then by using geometry and calculating with surds (square roots), then by taking a reading from a graph and finally by rearranging a formula into a quadratic equation and solving it.