Building blocks

## Problem

Use the slider to change the value of $a$.

• What do you notice?
• What questions do you have?

Decide which of the following is the gradient function of $\sin 3x$ and justify your answer.

1. $\cos 3x$
2. $3\cos x$
3. $3\cos 3x$

It may be useful to use the GeoGebra applet or graph sketching to help you explain.