 # Equilateral Triangle side = 13

## Enter Side (a) Given an equilateral triangle with side (a) equal to 13, calculate the other relevant items in this triangle

P = 3a
P = 3 x 13
P = 39

## Calculate Semiperimeter s:

 s  = P 2

 s  = 39 2

s = 19.5

## Calculate Area (A):

 A  = a2√3 4

 A  = 132√3 4

 A  = 169√3 4

 A  = 292.717 4

A = 73.179146619785

## Calculate Bisector

 ha-ma-ta  = a√3 2

 ha-ma-ta  = 22.5167 2

ha-ma-ta = 11.258330249198

 R  = a√3 3

 R  = 22.5167 3

R = 7.5055534994651

 r  = a√3 6

 r  = 22.5167 6

r = 3.7527767497326

P = 39
s = 19.5
A = 13

P = 39
s = 19.5
A = 13

### How does the Equilateral Triangle Calculator work?

Given a side (a), this calculates the following items of the equilateral triangle:
* Perimeter (P)
* Semi-Perimeter (s)
* Area (A)
* altitudes (ha,hb,hc)
* medians (ma,mb,mc)
* angle bisectors (ta,tb,tc)
This calculator has 1 input.

### What 3 formulas are used for the Equilateral Triangle Calculator?

1. P = 3a
2. s = ½P
3. A = a22√3/4

For more math formulas, check out our Formula Dossier

### What 6 concepts are covered in the Equilateral Triangle Calculator?

altitude
segment from the vertex of a triangle ot the other side of the triangle
area
Number of square units covering the shape
equilateral triangle
A triangle with 3 equal sides
perimeter
The distance around a shape or object