Angle
From Simple English Wikipedia, the free encyclopedia
An angle is the space between two lines that meet each other. When two lines meet at a point, an angle is formed. The two lines are called the arms of the angle. The point they meet is called the vertex.
To measure the size of an angle, we use degree. Degree is a standard unit. Degree is denoted by the symbol '°'. A degree can be divided into 60 minutes (1° = 60'), and a minute can be also be divided into 60 seconds (1' = 60"). In mathematics, angles are usually measured in radians.
[edit] Types of angles
An acute angle is an angle less than 90°. A right angle is an angle equal to 90°. An obtuse angle is an angle greater than 90°. A straight angle is an angle equal to 180°. A reflex angle is an angle greater than 180° but less than 360°.
Supplementary angles are two angles with the sum equal to 180°. Complementary angles are two angles with the sum equal to 90°.
People usually use a protractor to measure and draw angles. Sometimes, people use an angle ruler to measure angles.
