A cylinder with a radius of **r** and height **h** units has a volume of **V** cubic units. One of those simple formulas that tends to be forgotten.

By Automathic

0

Posted: 2013-09-16

Volume of a Cylinder

Volume of a Cylinder

$$$V = \pi r^2 h$$$

A cylinder with a radius of **r** and height **h** units has a volume of **V** cubic units. One of those simple formulas that tends to be forgotten.

By PiThagoras

0

Posted: 2013-09-16

Volume of a Triangular Prism

Volume of a Triangular Prism

$$$V = {1 \over 2} B * H * L$$$

A simple adaptation of the Area of a Triangle formula (http://automathic.org/114) to calculate the volume (**V**) of a *Triangular Prism* (https://en.wikipedia.org/wiki/Triangular_prism) with a base of **B**, height of **H**, and length of **L**.

By PiThagoras

0

Posted: 2013-09-16

Circumference of a Circle

Circumference of a Circle

$$$C = 2 \pi r = \pi d$$$

*"Circumference is the linear distance around the outside of a closed curve or circular object."* It can be calculated using the above, where **C** is the circumference using either the radius (**r**) or the diameter (**d**), depending on what's convenient.

More info can be found here: *https://en.wikipedia.org/wiki/Circumference*

By Isa McKenty

0

Posted: 2013-11-11

Radius of a Circle from its Area

Radius of a Circle from its Area

$$$r = \sqrt{A \over \pi}$$$

If you need to find the Radius ($$r$$) of a circle, and only have the Area ($$A$$) to work with, you can use this handy formula.

If you have the Circumference, use this formula: **www.automathic.org/152_radius-of-a-circle**

By Automathic

0

Posted: 2013-11-12

The Rules of Algebra

The Rules of Algebra

**Algebrarules.com** is Automathic's latest project, where you can find the rules of algebra for Arithmetic, Exponents, and Radicals — with more to come. It's *The Rules of Algebra, Sweet 'n Simple*.

By PiThagoras

0

Posted: 2013-12-20

Convert a Mixed Number to an Improper Fraction

Convert a Mixed Number to an Improper Fraction

$$$a{b \over c} = {a*c+b \over c}$$$

If you starting with a Mixed Number ($$a{b \over c}$$), use the above formula to convert it to an Improper Fraction (a fraction where the Numerator (top number) is greater than the Denominator (the bottom number))

By PiThagoras

0

Posted: 2014-02-04

Area of a Kite

Area of a Kite

$$$Area = { d_1 * d_2 \over 2}$$$

If you know the lengths of the diagonals — **d1** and **d2** — of a kite, finding the area is simple with the formula above.

Otherwise, you can use this method:

$$$ Area = a * b * sin(c) $$$

Where $$a, b$$ are the lengths of two unequal sides, and $$c$$ is the angle between them ($$sin$$ being the trignometric function sine **https://en.wikipedia.org/wiki/Sine**)

By Isa McKenty

0

Posted: 2014-02-05

Area of an Ellipse

Area of an Ellipse

$$$Area = \pi ab$$$

The area of an ellipse can be found when you know the measures of the major and minor semi-axis, $$a$$ and $$b$$.

Image courtesy of Wikimedia commons, licensed as creative commons.

By Isa McKenty

0

Posted: 2014-02-09

Surface Area of a Sphere

Surface Area of a Sphere

$$$4 \pi r^2$$$

The surface area of a sphere can be found with the above formula, where $$r$$ is the radius. It can also be notated as $$$\pi d^2$$$ Where $$d$$ is the diameter.

By PiThagoras

0

Posted: 2014-09-05

Improper Fraction to Mixed Number

Improper Fraction to Mixed Number

$$${a \over b} = quotient + {remainder \over divisor}$$$

To convert an Improper Fraction to a Mixed Number:

- • Divide the numerator by the denominator (with long division)
- • The result (quotient) of the division becomes the who part of the mixed number
- • The fractional part of the mixed number is the remainder over the original denominator

To convert the other way, use this formula: **http://automathic.org/158_convert-a-mixed-number-to-an-improper-fraction**

By Nathaniel

0

Posted: 2016-08-22

Inductors in series

Inductors in series

$$${L_t} = {L_1} + {L_2} + {L_3}$$$

Formula for inductors in series where L1 is the inductance of the first inductor, L2 is the inductance of the second inductor, L3 is the inductance of the third inductor, and L t is the total of all the inductors in series

By Nathaniel

0

Posted: 2016-08-22

Capacitors in parallel

Capacitors in parallel

$$${C_t} = {C_1} + {C_2} + {C_3}$$$

Formula for capacitors in parallel where C1 is the capacitance of the first capacitor, C2 is the capacitance of the second capacitor, C3 is the capacitance of the third capacitor, and C t is the total of all the capacitors in parallel

By Nathaniel

0

Posted: 2016-08-22

Capacitors in series

Capacitors in series

$$${1 \over C_t} = {1 \over C_1} + {1 \over C_2} + {1 \over C_3}$$$

Formula for capacitors in series where C1 is the capacitance of the first capacitor, C2 is the capacitance of the second capacitor, C3 is the capacitance of the third capacitor, and C t is the total of all the capacitors in series

By PiThagoras

0

Posted: 2016-09-30

Temperature Conversion (Celsius to Fahrenheit)

Temperature Conversion (Celsius to Fahrenheit)

$$$^{\circ}F = ^{\circ}C {\left(9 \over 5 \right)} + 32$$$

By PiThagoras

-1

Posted: 2013-01-17

Hero's Formula

Hero's Formula

$$$s= {a+b+c \over 2} \\ Area = s \sqrt{s(s-a)+s(s-b)+s(s-c)}$$$

Hero's Theorem is used to determine the **Area** of a Triangle with the side lengths **a b c** when you do not have the **Height** and **Base** measurements.

By Automathic

-1

Posted: 2013-03-07

Determining The Value of Pi

Determining The Value of Pi

$$$\pi = {C \over d}$$$

The constant Pi is equal to ~ (3.141592653589397....), and represents the ratio between a circle's circumference (**C**) and diameter (**d**) .

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