plane angle

An angle is a measure of the amount of rotation about the point of intersection of two lines or line segments that is required to bring one into correspondence with the other.

Given two intersecting lines or line segments, the amount of rotation about the point of intersection (the vertex) required to bring one into correspondence with the other is called the angle θ between them. The term "plane angle" is sometimes used to distinguish angles in a plane from solid angles measured in space. The term "angle" can also be applied to the rotational offset between intersecting planes about their common line of intersection, in which case the angle is called the dihedral angle of the planes. Angles are usually measured in degrees (denoted °), radians (denoted rad, or without a unit), or sometimes gradians (denoted grad).

acute angle | angle of attack | angle of incidence | angle standard position | arcminute | arcsecond | central angle | complementary angles | coterminal angle | degree | dihedral angle | directed angle | Euler angles | exterior angle | full angle | gradian | horn angle | initial side | inscribed angle | oblique angle | obtuse angle | protractor | radian | reflex angle | right angle | solid angle | steradian | straight angle | subtend | supplementary angles | terminal side | vertex angle

elementary school level (California grade 3 standard)