**1. Are there any other units for measuring angles besides degrees and minutes?**

Yes.

The other system is called radians. You can change themodeof your calculator to operate using radians (RAD) instead of degrees (DEG). Remember to change it back!

**2. Why are there 360 degrees in a one revolution?**

The Zodiac was first divided into 360. The Greek astronomer Hipparchus first divided a circle into 360 degrees. 360 is also approximately the number of days in a year.

**3. Are vertically opposite angles always equal?**

Providing the two intersecting lines are both straight lines.

**4. Are congruent angles and equal angles the same thing?**

Yes.

A pair of congruent angles are the same size and a pair of equal angles are the same size.