 # Equilateral Triangle side = 18

## Enter Side (a) Given an equilateral triangle with side (a) equal to 18, calculate the other relevant items in this triangle

P = 3a
P = 3 x 18
P = 54

## Calculate Semiperimeter s:

 s  = P 2

 s  = 54 2

s = 27

## Calculate Area (A):

 A  = a2√3 4

 A  = 182√3 4

 A  = 324√3 4

 A  = 561.184 4

A = 140.29611541308

## Calculate Bisector

 ha-ma-ta  = a√3 2

 ha-ma-ta  = 31.1769 2

ha-ma-ta = 15.58845726812

 R  = a√3 3

 R  = 31.1769 3

R = 10.392304845413

 r  = a√3 6

 r  = 31.1769 6

r = 5.1961524227066

P = 54
s = 27
A = 18

P = 54
s = 27
A = 18

### 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