obtuse angle definition. An angle that measures more than 90 degrees but less than 180 degrees. (Compare acute angle and right angle.)

POINT

• a dot or other punctuation mark, in particular a period.

LINE

• 1. a long, narrow mark or band.

PLANE

• plane is a flat, two-dimensional surface. A plane is the two-dimensional analogue of a point

COPLANAR LINES

• Coplanar lines are lines that lie on the same plane.

SKEW LINES

• skew lines are two lines that do not intersect and are not parallel

ARC

• 1. a part of the circumference of a circle or other curve.

CONGRUENT

• (of figures) identical in form; coinciding exactly when superimposed.

ANGLE

• 1. the space (usually measured in degrees) between two intersecting lines or surfaces at or close to the point where they meet.

VERTEX

• 1. the highest point; the top or apex. synonyms:

ACUTE ANGLE

• acute angle definition. An angle that measures less than ninety degrees but more than zero degrees

RIGHT ANGLE

• an angle of 90°, as in a corner of a square or at the intersection of two perpendicular straight lines.

STRAIGHT

• an angle of 180°.

CONGRUENT ANGLES

• Congruent. Exactly equal in size and shape. Congruent sides or segments have the exact same length.

SUPPLEMENTARY ANGLES

• either of two angles whose sum is 180°.

COMPLEMENTARY ANGLES

• either of two angles whose sum is 90°.

PERPENDICULAR

• at an angle of 90° to a given line, plane, or surface.

ADJACENT ANGLES

• Adjacent angles are two angles that have a common vertex and a common side.