Equilateral triangle calculator

An equilateral triangle is a triangle where all three sides have the same length, and all three angles are also congruent and measure 60 degrees each.

If you know the length of one side of an equilateral triangle (a), you can use that information to find the perimeter (p) of the triangle: p = 3a

You can also use the side length to find the area of the triangle using the formula:

Area = (√3/4) * a²

You can also use the side length to find the height (h) or the inradius (r) of the triangle:

h = (a√3)/2
r = a/(2√3)

If you know the area of an equilateral triangle, you can use that information to find the length of one side (a) using this formula:
Area = (√3/4) * a²

You can also use the area to find the height (h) or inradius (r) of the triangle:

h = (2 * √(3 * area))/a
r = √((2 * area)/√3)

If you know the height (h) of an equilateral triangle, you can use that information to find the length of one side (a) using this formula:

a = (2 * h)/√3

Calculate an equilateral triangle by:

• side a
• area S
• height h

An equilateral triangle in word problems in mathematics:

• Triangle
  Can an equilateral triangle have a right angle?
• Equilateral RT
  On a right triangle, side a is 12, and side b is 12. What is side c?
• Calculate
  Calculate the length of a side of the equilateral triangle with an area of 50cm².
• Equilateral Δ
  What is the area of an equilateral triangle with a circumference of 63 cm?
• An equilateral triangle
  The perimeter of an equilateral triangle is 33cm. How long is each side?
• Triangular numbers
  The first four triangular numbers are 1,3,6,10. What is the 10th triangular number? Help: A triangular number or triangle number counts objects arranged in an equilateral triangle.
• Equilateral triangle v3
  Calculate an equilateral triangle's perimeter and area with a side of 20 dm.
• Equilateral triangle v2
  Calculate the side of an equilateral triangle if its perimeter is 132 cm.
• Equilateral triangle
  Find the area of an equilateral triangle with a side of 15 cm.
• Equilateral triangle v2
  An equilateral triangle has a perimeter 36 dm. What is its area?
• Equilateral triangle
  Calculate the side of an equilateral triangle if its area is 886 mm².
• Semicircle
  The semicircle with center S and the diameter AB is constructed equilateral triangle SBC. What is the magnitude of the angle ∠SAC?
• Height UT
  How long is the height in the equilateral triangle with a side f = 31?
• Equilateral triangle
  The equilateral triangle has a 23 cm long side. Calculate its area.
• The perimeter 12
  The perimeter of an equilateral triangle is 41.46 inches. If the length of each side is (q - 5.7), what is the value of q?

more triangle problems »

Also, take a look at our friend's collection of math problems and questions!

• Equilateral triangle
• triangle
• right triangle
• Heron's formula
• The Law of Sines
• The Law of Cosines
• Pythagorean theorem
• triangle inequality
• similarity of triangles
• The right triangle altitude theorem

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