**1. Why is there more than one system for measuring angles?**

Mathematicians, engineers and scientists like to use radians because of the connection with π and circles.

Most everyday measuring of angles is done in degrees.

**2. Which system of measuring angles should I use?**

The formulae for the length of an arc and the area of a sector must use radians.

When doing geometry it is usual to use degrees.

Calculators can be set to either

DEGorRAD.

**3. Can I leave π in my final answer or do I have to work it out?**

π can usually be left in a final answer unless the question requires an answer to a specified level of accuracy e.g. 2 significant figures.

**4. Which angle mode should I set my calculator?**

It is probably best to have the calculator on degree (DEG) mode normally and change it to radian (RAD) when using sine, cosine and tangent ratios given in radians.