Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

This is an AMP page - Open full page! for all features.

• the most efficient way to navigate the Engineering ToolBox!

# Law of Sines

## Calculate the angles in a generic triangle.

The "Law of Sines" can be used to calculate the angles of a triangle.

The "Law of Sines" can be expressed as

$${a \over sin A } = {b \over sin B } = {c \over sin C } \tag{1}$$

where

a, b and c = length of sides in triangle (m, ft ...)

A, B and C = angles in the triangle (degrees)

### Law of Sines Calculator

a (m, ft ....)

b (m, ft ....)

A (degrees)

Eq. 1 can be modified to

$$a = {b sin A \over sin B } = {c sin A \over sin C } \tag{1a}$$

$$b = {a sin B \over sin A } = {c sin B \over sin C } \tag{1b}$$

$$c = {a sin C \over sin A } = {b sin C \over sin B } \tag{1c}$$

This expression can also be handy:

$$sin \frac{1}{2}A = \sqrt{{(s - b)(s - c) \over b c }} \tag{2}$$

where

$$s = \frac{1}{2}(a + b + c) \tag{3}$$

## Related Topics

• Mathematics - Mathematical rules and laws - numbers, areas, volumes, exponents, trigonometric functions and more.

## Search Engineering ToolBox

• the most efficient way to navigate the Engineering ToolBox!

## SketchUp Extension - Online 3D modeling!

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp from the Sketchup Extension Warehouse!

## Privacy

We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.

Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.

Temperature

oC
oF

Length

m
km
in
ft
yards
miles
naut miles

Area

m2
km2
in2
ft2
miles2
acres

Volume

m3
liters
in3
ft3
us gal

Weight

kgf
N
lbf

Velocity

m/s
km/h
ft/min
ft/s
mph
knots

Pressure

Pa (N/m2)
bar
mm H2O
kg/cm2
psi
inches H2O

Flow

m3/s
m3/h
US gpm
cfm

6 24