Solve for x regarding the length of a side as follows: x = the length of any other side. For instance, if side "y" equals 2 inches and you must solve for side "x," then x would also equal 2 inches.
Solve for x regarding an angle as follows: x = the degree of any other angle within the equilateral triangle. You also can say that x = 60 degrees, since equilateral triangles always have three angles that equal 60 degrees each. Therefore, in terms of an angle, x = 60.
Find x in terms of the perimeter of an equilateral triangle as follows: x = length of a side * 3. For example, if the length of one side is 5 inches, multiply 5 times 3 to get a perimeter of 15 inches.
Find x as the area of an equilateral triangle as follows: x = √3/4(S^2). In this formula, "S" stands for the length of a side. Consider an example equilateral triangle in which the length of a side equals 3 inches. Take the square root of 3, which equals 1.732. Divide this by 4 to get 0.433. Multiply this quotient by the side squared, which equals 9 (3 times 3). Your final answer would be 9 times 0.433, which equals 3.897 square inches.