# Ch 6 Geometry

## 54 terms · Geometry Vocab

### point

the simplest figure in geometry, representing an exact location

### line

a figure determined by two points and extending in both directions without end

### plane

a flat surface extending infinitely in all directions

### collinear points

two or more points that lie on the same line

### segment

two points on a line and all the points between them

### endpoint

the point at the end of a line segment or ray

### congruent sides/segments

sides or segments that have the exact same length

### midpoint

the point of a segment that divides it into two congruent segments

### ray

a part of a line with one endpoint

### coplanar

lying in the same plane

### circle

a plane figure made up of all points that are the same distance from a given point in the plane

### center

the point that lies equidistant from all point on a circle or a sphere

a line segment joining any point on a circle or sphere to the center

### chord

a segment that joins two points on a circle

### diameter

a chord that contains the center of a circle or a sphere

### arc

a part of a circle

half of a circle

### circumference

the perimeter of a circle

### angle

a figure formed by two rays with a common endpoint

### vertex of an angle

the common endpoint of two intersecting rays

### acute angle

an angle with measure between 0 and 90 degrees

### obtuse angle

an angle with measure between 90 and 180 degrees

### right angle

angle with measure 90 degrees

### straight angle

an angle with measure 180 degrees

### congruent angles

angles that have the exact same measure

two angles with a common side and a common vertex, but with no common points in their interiors

### bisect

to divide a geometric figure into two congruent parts

### parallel lines

lines in the same plane that do not intersect

### perpendicular lines

two lines that intersect to form four right angles

### complementary angles

two angles whose measures have a sum of 90 degrees

### supplementary angles

two angles whose measures have a sum of 180 degrees

### vertical angles

the angles opposite each other when two lines intersect to form four angles

### triangle

a polygon with three sides

### acute triangle

a triangle with three acute angles

### right triangle

a triangle with a right angle

### obtuse triangle

a triangle that has one obtuse angle

### scalene triangle

a triangle with no two sides congruent

### isosceles triangle

a triangle with at least two sides congruent

### equilateral triangle

a triangle in which all sides are congruent

a polygon with four sides

### parallelogram

a quadrilateral with both pairs of opposite sides parallel

### rhombus

a parallelogram in which all sides are congruent

### rectangle

a quadrilateral with four right angles

### square

a rectangle with all four sides congruent

### trapezoid

a quadrilateral with exactly one pair of parallel sides

### diagonal

a segment that joins two non-consecutive vertices of a polygon

### polygon

a closed plane figure made up of line segments

### vertex of a polygon

the point at which two sides of a polygon intersect

### perimeter

the distance around a plane figure

### pentagon

a polygon with five sides

### hexagon

a polygon with six sides

### octagon

a polygon with eight sides

### decagon

a polygon with ten sides

### regular polygon

a polygon in which all sides are congruent and all angles are congruent