Triangle calculator

Please enter what you know about the triangle:
Symbols definition of ABC triangle

The calculator solves the triangle specified by three of its properties. Each triangle has six main characteristics: three sides a, b, c, and three angles (α, β, γ). The classic trigonometry problem is to specify three of these six characteristics and find the other three. Of course, our calculator solves triangles from combinations of main and derived properties such as area, perimeter, heights, medians, etc. Usually by the length of three sides (SSS), side-angle-side, or angle-side-angle.

How does this calculator solve a triangle?

The calculation of the general triangle has two phases:
  1. The expert phase is different for different tasks. The calculator tries to calculate the sizes of three sides of the triangle from the entered data. He gradually applies the knowledge base to the entered data, which is represented in particular by the relationships between individual triangle parameters. These are successively applied and combined, and the triangle parameters are calculated. Calculator iterates until the triangle has calculated all three sides.
    For example, the appropriate height is calculated from the given area of the triangle and the corresponding side. From the known height and angle, the adjacent side, etc., can be calculated. The calculator uses use knowledge, e.g., formulas and relations like the Pythagorean theorem, Sine theorem, Cosine theorem, and Heron's formula.
  2. The second stage is the calculation of the properties of the triangle from the available lengths of its three sides.

Examples of how to enter a triangle:

a=3 b=4 c=5 ... triangle calc by three sides a,b,c.
B=45 c=10 a=9 ... triangle calc by two sides a,c and included angle B.
A=25 C=80 b=22
A=35 C=26 a=10
a=3 C=90 c=5 ... how to enter right-angled triangle.
a=3 β=25 γ=45 ... triangle calc if we know the side and two angles.
a=3 β=25 T=12 ... triangle calc, if know side, angle, and area of a triangle.
T=2.5 c=2 b=4 ... find side a if we know sides b, c, and the area of triangle T.
ma=1 b=2.5 c=2 ... calculation of the triangle if we know one median and any two sides.
ma=1 mb=2.5 mc=2 ... triangle calc by three medians.
ha=220, hb=165 hc=132 ... triangle calc by three heights.
a=7 β=40 mc=5 ... triangle calc by one side, one angle, and one median.
a:b:c=2:3:4 T=2.5 ... a triangle where the known side ratio and its area.
A:B:C=1:4:5 a=2 ... calculating triangle if we know the ratio of the internal angles and one side.
What do the symbols mean?

a, b, c ... sides BC, AC, AB
A, B, C or α, β, γ ... internal angles
ha, hb, hc ... altitudes (heights)
ma, mb, mc ... medians
T ... area
p ... perimeter
s ... semiperimeter

Triangles in word problems:

more triangle problems »

Look also at our friend's collection of math problems and questions:

See triangle basics on Wikipedia or more details on solving triangles.