# Basic Geometry

## 20 terms

### Octogon

polygon with 8 sides

### rhombus

polygon with four sides, two sets of parallel line, no right angles, all equal sides

### right angle

an angle that measures 90 degrees

### trapezoid

quadrilateral with exactly one pair of oposite parellel sides

### hexagon

a polygon with six sides

### square

a quadrilaterial with four right angles, and all sides equal

### acute

an angle that measures less than 90 degrees

### obtuse

an angle that measures more than 90 degrees

### equilateral triangle

a triangle with all three sides equal and all three angles equal

### parallel line

lines that will never cross

### perpendicular lines

lines that cross at 90 degree angles

### pentagon

a polygon with five sides

### convex polygon

a polygon that only has angles that bulges outward

### concave

a polygon that has at least one angle that points inside the shape

### concentric

a series of the same shape, but of different sizes which have a common center

### congruent

Having the same size and shape

a four-sided polygon

### regular polygon

a polygon with all sides and all angles equal

### polygon

a closed figure formed by three or more line segments

### line segment

part of a line with two endpoints