ANGLES
Angles are constantly used in geometry. They are
basically two rays starting at the same point. The point at which they start is
called the vertex, and the rays are called the sides.
Angles can be measured, but not in the same way
as segments can. They are also classified through letters, and likewise have to
be designated in the correct manner. Angle ABC, also shown as <ABC, must be
referred to as <ABC. The reason is that the middle letter is always the
vertex, and if you say <BAC the angle would be completely different.
In this illustration, you can see that saying
<BAC would be impossible, and that <ABC would be the correct name.
Next comes the measurement of angles. The concept
of measuring an angle is different from that off measuring a segment. You don't
find the length of the sides; you basically find the distance of the
"gap" between the sides. This is measured in degrees.
As you can see, the measure of <ABC is 60
degrees.
Also in angles, there can be more than two rays
emanating from a vertex, thus making sides within sides of an angle.
Now you can see why calling an angle by its correct name
is so important.
