Posts Tagged ‘radius’
Thursday, November 19th, 2009
How to Determine the Center of a Circle
Description
A detailed tutorial on how to determine the center of a circle. Step by step tutorial including several examples of the center of a circle for reference.
Overview
The center of the circle is very easy to find. It is one of the endpoints of the radius and the midpoint of the diameter. The video shows you how to find it based on a series of accurate drawing. However, there is a mathematical way to find the center of the circle, which is also sometimes called the origin of the circle. Just use the midpoint formula with the diameter. If you have the radius just multiply it by two, because you cannot use the distance formula without already having the coordinates of the origin.
Tags: center, circle, coordinates, diameter, distance, endpoint, formula, mathematical, midpoint, origin, point, radius
Posted in Algebra | No Comments »
Tuesday, November 17th, 2009
Overview of Half-Circles
Description
A detailed tutorial on equations of a half-circle. Step by step tutorial including several examples and an explanation of half-circles for reference.
Overview
A half-circle is truely half of a circle. If you take a circle and cut it in half, you will get a half circle. Because of this, the equations of the half-circle are very similar to the equations of a full circle – simply divide the equation by two. The only ones that you cannot find that way are the radius, diameter, and circumference. The radius and diameter do not change on a half-circle. There is no circumference on the half-circle, but if you need the circumference for another formula you can use the circumference of the whole circle of that half-circle.
Tags: area, basic, circle, circumference, coordinates, cut, diameter, divide, equation, Geometry, half, half-circle, pi, radius, shape, split, two, whole
Posted in Geometry | No Comments »
Tuesday, November 10th, 2009
An Overview of Pi
Description
A detailed tutorial on what pi is. Step by step tutorial including several examples of what pi is for reference.
Overview
Pi is a special number in mathematics. It is the ratio of a circle’s circumference to its diameter. No matter what size circle you use, your answer will always be pi, showing that all circles are proportional to one another. Pi is denoted by the Greek letter pi, which looks a little bit like an “n”. The numerical value of pi is 3.1415926535… but is typically shortened to the simple 3.14. Pi is very important in math and is used in all equations dealing with circles.
Tags: 3.14, arithmetic, circle, circumference, denoted, diameter, equations, Greek, letter, pi, propertional, radius, ration, size, value
Posted in Arithmetic | No Comments »
Friday, September 11th, 2009
How to Find the Equation of a Circle
Description
A detailed tutorial on how to find the equation of a circle. Step by step tutorial including several examples of how to find the equation of a circle for reference.
Overview
The equation of a circle is really the distance from the point (h, k) – the center of the circle – to the point (x, y) – a point somewhere on the outside of the circle. This distance will be called r. Having this information, we can now insert it into the distance formula:
r = sqrt[(x - h)^2 + (y - k)^2]
But because no one wants to solve a square root, we can simplify the formula and get rid of the square root entirely:
r^2 = (x – h)^2 + (y – k)^2
This is the general formula for a circle. You must always have the center and radius of a circle to be able to solve. However, even if you are not given these you can easily find them by using the distance and midpoint formulas with whatever points you are given.
Tags: algebra, center, circle, distance formula, equation, equation of a circle, Geometry, Math, midpoint, Outside, points, radius
Posted in Algebra | No Comments »
Tuesday, September 8th, 2009
How to Find the Volume of a Cone
Description
This video gives an easy visual demonstration of the differences in volumes of two different shapes – a cone and a cylinder. The video proves that the formula must be different, because even though the height and base are exactly the same the volume is definitely not the same.
Overview
A cone is a pyramid that has the base shape of a cylinder instead of a rectangular prism. The volume of a cone can be expressed as:
V = (1/3) * B * h
Where h is the height, and B is the area of the base – the area of the base is the area of a circle, and can be expressed as pi * r^2.
Tags: area, base, circle, cone, finding volume, Geometry, height, Math, pi, radius, volume, volume of a cone
Posted in Geometry | No Comments »
Friday, September 4th, 2009
How to Find the Volume of a Cylinder
Description
This video gives two different ways that you can find the volume of a cylinder. It provides the volume formula and several example problems.
Overview
Finding the volume of a cylinder is not hard – all you need is to find the right values. The volume of a cylinder can be expressed as:
V = pi * r^2 * h
The variable r represents the raidus of the circle found on the bottom and top of the cylinder, normally called the base. The variable h represents the height of the cylinder. Pi is a number equal to approximately 3.14.
Tags: cylinder, finding volume, Geometry, height, Math, pi, radius, volume, volume of a cylinder
Posted in Geometry | No Comments »
Thursday, September 3rd, 2009
Parts and Equations of Circles
Description
This video explains all the different parts of the circle, with multiple picture examples. Everything is laid out in an easy to read format and the illustrations clearly show where on the circle each part is located.
Overview
Circles are very interesting shapes in the world of geometry. There are many different parts to a circle, and many different formulas. The most common formulas are the area and the circumference formula.
Area Formula: Area = pi * radius * radius = pi * radius^2
Circumference Formula: Circumference = pi * diameter = pi * 2 * radius
The area is the area inside a circle, and the circumference is the measurement of the outside of the circle. The diameter is the width of the circle, and the radius is half of the diameter. Pi is a number that is equal to approximately 3.14.
The other parts of a circle are the sector, chord, arc, tangent, and secant. These are lines that will not show up all the time and will not always need to be acknowledged, but they do exist on the circle.
Tags: arc, area, chord, circle, circumference, diameter, Geometry, Math, pi, radius, secant, sector, tangent
Posted in Geometry | No Comments »
