### Geometry Review and Resources

Concepts in geometry will pop up again and again in nearly any math class you take - from algebra to calculus. This article presents you with a review of the basics and provides brief resources that you can use to test your skills. The following terms and definitions are basic geometry terms you should be familiar with:

1) Line

2) Point

3) Intersection

4) Line segments

5) Rays

6) Endpoints

7) Parallel Lines

#### Line:

Line is a basic term in geometry. Lines extend infinitely in both directions. The name of a line which passes through points A and B is expressed as 'line AB' or as AB with a two-headed arrow on top.

#### Point:

Point is one of geometry's basic terms. A point is often pictured as a 'dot' and is identified with a number or a letter. The point does not have length or width, but does have an exact location.

#### Intersection:

The term intersect means lines, line segments, rays or figures that meet or share a common point. This common point is referred to as the point of intersection.

#### Line Segments:

A line segment is a line that does not extend indefinitely, but has two endpoints. The line segment whose endpoints are points A and B is written as 'line segment AB' or as simply 'AB'.

#### Rays:

A ray is a straight line beginning at one certain point and extending forever in the opposite direction. The point is known as the ray's endpoint, and a ray whose endpoint is A and which passes through point B is expressed as 'ray AB' or as 'AB' with an arrow head over the 'B'.

#### Endpoints:

The endpoint defines either a line segment (2 endpoints) or a ray (1 endpoint).

#### Parallel Lines:

Parallel lines lie in the same plane yet never intersect. Two line segments parallel one another if the lines on which they lie parallel one another as well. When line 2 parallels line 1, this is written as line 2 || line 1. When two line segments AB and DC lie on parallel lines, this is written as as segment AB || segment DC.

#### Geometric Figures

Now we focus on slightly more complex geometric figures. In geometry, there are four types of angles:

1) Acute angles are between 0 and 90 degrees

2) Right angles have 90 degrees

3) Obtuse angles are between 90 and 180 degrees

4) Straight angles have 180 degrees

#### Triangles

From these angles we can form the different types of triangles, for triangles are described by their angles. The four types of triangles are as follows:

1) Acute triangles are triangles with three acute angles.

2) Obtuse triangles are triangles which have one obtuse angle and two acute angles.

3) Right triangles have one right angle and two acute angles.

4) Equiangular triangles are triangle with all congruent angles.

#### Circles

Finally, to complete our short review of basic geometric shapes we have the circle. The most common questions involving circles require that you do two things: find the area of a circle, or find the circumference of a circle.

Area of a Circle:

1) The radius of the circle measures the distance from its center to outside edge.

2) If only the diameter is known, it can be divided by 2 to determine the radius.

3) Square the radius (multiply it by itself), then multiply the answer (radius squared) by pi (3.1416) to find the area of the circle.

Circumference of a Circle:

1) The diameter of a circle is the distance across its middle from one side to the other.

2) If only the radius (the distance from the center to the outside) of the circle is known, multiply it by 2 to determine the diameter.

3) The diameter multiplied by pi (3.1416) equals the circumference.

4) Divide the diameter by 0.3183 - this is the circumference.

#### Online Resources

Now that you have had a brief review, why don't you test your skills? Free math tests are available online that will allow you (without giving any information about yourself) to be tested on a number of math areas. Just type 'Online Geometry Test' into a search engine to find these sites.

In addition, search this site for other questions you may have about math help. Otherwise, check the internet for your other questions, go the library to find helpful books, visit a tutoring center, contact a professor at a local university or junior college, or ask a math savvy friend. Any help that assists you in reaching your academic goals is good help. Good luck!