# Bien Chapter 9

## 24 terms

### Square

4 equal (congruent) sides. 90 degree angles.

### Rectangle

A parallelogram with 4 right angles.

A polygon with 4 sides

### Right Angle

A special angle formed by perpendicular lines and with a measure of 90 degrees.

### Triangle

3 sides and 3 angles. (3-sided polygon)

### Acute Triangle

3-sided polygon, 1 angle greater than 90 degrees

### Obtuse angle

An angle that has a measure that is greater than 90 degrees and less than 180 degrees.

### Isosceles Triangle

3 sided triangle(polygon) with at LEAST 2 congruent(equal) sides.

### Equilateral Triangle

A triangle with 3 congruent sides. (3-sided polygon-it also has three 60 degree angles).

### parallelogram

A quadrilateral with 2 pairs of parallel sides.

### parallel lines

Lines or figures in a plane that never intersect.

### trapezoid

A quadrilateral with exactly one pair of parallel sides.

### congruent

same size, same shape

### rhombus

A parallelogram with 4 congruent(equal) sides.

### vertex or vericies

The point where 2 or more rays meet; the point of intersection of 2 sides of a polygon; the point of intersection of 3 or more edges of a 3-dimensional figure.

### polygon

enclosed figure; 2D; 3 or more line segments.

### Acute Angle

An angle that has a measure less than a right angle (90 degrees)

### Concave

Used to describe a polygon with at least one angle measuring more than 180 degrees.

### Kite

A quadrilateral with no parallel sides, two pairs of contruent sides, 1 line of symmetry, and all vertices are convex

### Opposite Angles

Angles that touch only at their vertex and share the same lines as sides.

### Perpendicular Lines

Two lines that intersect to form right angles.

### Similar

having the same shape, but not necessarily the same size

### Straight Angle

An angle that has a measure of 180 degrees

### Trapezoid

A quadrilateral with exactly one pair of parallel sides