Lesson Worksheet: Equilateral Triangles Mathematics • 11th Grade

In this worksheet, we will practice identifying equilateral triangles by their equal side lengths or equal angle measures to find a missing side length, perimeter, or area.


Find the perimeter of the shape below.


One side of an equaliteral triangle has length (4𝑥+7). Another side has length (3𝑥+8). Find the perimeter of the triangle.


The perimeter of an equilateral triangle is equal to the perimeter of a rectangle with a length of 5 cm and a width of 4 cm. Find the length of one side of the triangle.


Find the perimeter of 𝐴𝐵𝐶.


In the figure below, 𝐴𝐵𝐶 is an equilateral triangle, 𝐷𝐵=𝐷𝐶, and 𝑚𝐵𝐷𝐶=112. Find 𝑚𝐴𝐵𝐷.


The area of an equilateral triangle is 2563 cm2. Find the side length.


The diagram shows an equilateral triangle. Find the length of its sides.


What is the ratio of the length of a side of an equilateral triangle to its perimeter?

  • A12
  • B11
  • C13
  • D21
  • E31


A triangle has three sides equal in length and a perimeter of 24 length units. Find the length of one of its sides.


Calculate the length of one of the sides of an equilateral triangle which has a perimeter of 93 m.

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