Classification

= Good Job ! ! = =Classification= Classification is a rhetorical function used to organize information according to categories. For example:

Types of angles

 * [[image:http://upload.wikimedia.org/wikipedia/commons/thumb/6/6c/Right_angle.svg/134px-Right_angle.svg.png width="134" height="134" caption="Right angle." link="http://en.wikipedia.org/wiki/Image:Right_angle.svg"]] || [[image:http://upload.wikimedia.org/wikipedia/commons/thumb/5/59/Reflex_angle.svg/96px-Reflex_angle.svg.png width="96" height="134" caption="Reflex angle." link="http://en.wikipedia.org/wiki/Image:Reflex_angle.svg"]] || [[image:http://upload.wikimedia.org/wikipedia/commons/thumb/2/22/Complement_angle.svg/134px-Complement_angle.svg.png width="134" height="134" caption="The complementary angles a and b (b is the complement of a, and a is the complement of b)." link="http://en.wikipedia.org/wiki/Image:Complement_angle.svg"]] || [[image:http://upload.wikimedia.org/wikipedia/commons/thumb/e/ee/Angle_obtuse_acute_straight.svg/241px-Angle_obtuse_acute_straight.svg.png width="241" height="134" caption="Acute (a), obtuse (b), and straight (c) angles. Here, a and b are supplementary angles." link="http://en.wikipedia.org/wiki/Image:Angle_obtuse_acute_straight.svg"]] ||


 * An angle of 90° (//[|π]///2 radians, or one-quarter of the full circle) is called a **[|right angle]**. Two lines that form a right angle are said to be **[|perpendicular]** or **[|orthogonal]**.
 * Angles smaller than a right angle (less than 90°) are called **acute angles** ("acute" meaning "sharp").
 * Angles larger than a right angle and smaller than two right angles (between 90° and 180°) are called **obtuse angles** ("obtuse" meaning "blunt").
 * Angles equal to two right angles (180°) are called **straight angles**.
 * Angles larger than two right angles but less than a full circle (between 180° and 360°) are called **reflex angles**.
 * Angles that have the same measure are said to be **[|congruent]**.
 * Two angles opposite each other, formed by two intersecting straight lines that form an "X" like shape, are called **[|vertical angles]** or **opposite angles**. These angles are congruent.
 * Angles that share a common vertex and edge but do not share any interior points are called **[|adjacent angles]**.
 * Two angles that sum to one right angle (90°) are called **[|complementary angles]**. The difference between an angle and a right angle is termed the **complement** of the angle.
 * Two angles that sum to a straight angle (180°) are called **[|supplementary angles]**. The difference between an angle and a straight angle is termed the **supplement** of the angle.
 * Two angles that sum to one full circle (360°) are called **explementary angles** or **conjugate angles**.
 * An angle that is part of a [|simple polygon] is called an **[|interior angle]** if it lies in the inside of that the simple polygon. Note that in a simple polygon that is concave, at least one interior angle exceeds 180°. In [|Euclidean geometry], the measures of the interior angles of a [|triangle] add up to //π// radians, or 180°; the measures of the interior angles of a simple [|quadrilateral] add up to 2//π// radians, or 360°. In general, the measures of the interior angles of a [|simple polygon] with //n// sides add up to [(//n// − 2) × //π//] radians, or [(//n// − 2) × 180]°.
 * The angle supplementary to the interior angle is called the **[|exterior angle]**. It measures the amount of "turn" one has to make at this vertex to trace out the polygon. If the corresponding interior angle exceeds 180°, the exterior angle should be considered [|negative]. Even in a non-simple polygon it may be possible to define the exterior angle, but one will have to pick an [|orientation] of the [|plane] (or [|surface]) to decide the sign of the exterior angle measure. In Euclidean geometry, the sum of the exterior angles of a simple polygon will be 360°, one full turn.
 * Some authors use the name **exterior angle** of a simple polygon to simply mean the explementary (//not// supplementary!) of the interior angle [|[1]]. This conflicts with the above usage.
 * The angle between two [|planes] (such as two adjacent faces of a [|polyhedron]) is called a **[|dihedral angle]**. It may be defined as the acute angle between two lines [|normal] to the planes.
 * The angle between a plane and an intersecting straight line is equal to ninety degrees minus the angle between the intersecting line and the line that goes through the point of intersection and is normal to the plane.
 * If a straight [|transversal line] intersects two [|parallel] lines, corresponding (alternate) angles at the two points of intersection are congruent; [|adjacent angles] are [|supplementary] (that is, their measures add to //π// radians, or 180°).

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