Equilateral Triangle Calculator

Input one known parameter: side length, height, perimeter, or area, and instantly calculate the height, perimeter, and area of an equilateral triangle.

Calculate the Height, Perimeter, and Area of an Equilateral Triangle

Side Length

Height

Perimeter

Area

How to Calculate Properties of an Equilateral Triangle

1. Given Side Length (\( a \))

Height (\( h \)): \( h = \frac{\sqrt{3}}{2} \times a \)

Perimeter (\( P \)): \( P = 3 \times a \)

Area (\( A \)): \( A = \frac{\sqrt{3}}{4} \times a^2 \)

2. Given Height (\( h \))

Side Length (\( a \)): \( a = \frac{2h}{\sqrt{3}} \)

Perimeter (\( P \)): \( P = 3 \times a = 2\sqrt{3}h \)

Area (\( A \)): \( A = \frac{\sqrt{3}}{4} \times a^2 = \frac{h^2}{\sqrt{3}} \)

3. Given Perimeter (\( P \))

Side Length (\( a \)): \( a = \frac{P}{3} \)

Height (\( h \)): \( h = \frac{\sqrt{3}}{2} \times a = \frac{P}{2\sqrt{3}} \)

Area (\( A \)): \( A = \frac{\sqrt{3}}{4} \times a^2 = \frac{P^2}{12\sqrt{3}} \)

4. Given Area (\( A \))

Side Length (\( a \)): \( a = \sqrt{\frac{4A}{\sqrt{3}}} \)

Height (\( h \)): \( h = \frac{\sqrt{3}}{2} \times a = \sqrt{\sqrt{3}A} \)

Perimeter (\( P \)): \( P = 3 \times a = 6 \times \sqrt{\frac{A}{\sqrt{3}}} \)

Examples

Example 1: Given side length \( a = 10 \), find the Height, Perimeter and Area.

Solution:

Height:

\(h = \frac{\sqrt{3}}{2} \times 10 \approx 8.66\)

Perimeter:

\(P = 3 \times 10 = 30\)

Area:

\(A = \frac{\sqrt{3}}{4} \times 10^2 \approx 43.3\)

Example 2: Given height \( h = 6 \), find the Side Length, Perimeter and Area.

Solution:

Side Length:

\( a = \frac{2 \times 6}{\sqrt{3}} \approx 6.93 \)

Perimeter:

\( P = 3 \times 6.93 \approx 20.79 \)

Area:

\( A = \frac{\sqrt{3}}{4} \times 6.93^2 \approx 20.79 \)

Example 3: Given perimeter \( P = 36 \), find the Side Length, Height and Area.

Solution:

Side Length:

\( a = \frac{36}{3} = 12 \)

Height:

\( h = \frac{\sqrt{3}}{2} \times 12 \approx 10.39 \)

Area:

\( A = \frac{\sqrt{3}}{4} \times 12^2 \approx 62.35 \)

Example 4: Given area \( A = 100 \), find the Side Length, Height and Perimeter.

Solution:

Side Length:

\( a = \sqrt{\frac{4 \times 100}{\sqrt{3}}} \approx 15.19 \)

Height:

\( h = \frac{\sqrt{3}}{2} \times 15.19 \approx 13.15 \)

Perimeter:

\( P = 3 \times 15.19 \approx 45.59 \)