1. How can I measure an angle of 250 degrees when the protractor only goes up to 180 degrees?

One of the arms of the angle is extended to make a straight angle of 180 degrees. The rest of the angle can then be measured using the protractor.

2. What is the difference between a compass, compasses and a pair of compasses?

compass is used to find directions. It points to magnetic north.

A pair of compasses is an instrument used in geometry to draw cirlces and arcs.

Compasses is a shortened version of a pair of compasses.

3. Why are there two types of set square?

Both have angles of 90 degrees (one of the corners is a right angle).

One type has two corners with angles of 45 degrees.

The other type has one corner with an angle of 60 degrees and the other of 30 degrees.