The name of the triangle that has all sides of same length.

Correct option is D

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A triangle with all three sides of equal length is called an equilateral triangle. In this type of triangle, all three angles are also equal, each measuring 60°. It is a special case of an isosceles triangle, which has at least two equal sides.
Equilateral triangles have perfect symmetry and are commonly used in architecture, engineering, and design. The area of an equilateral triangle is given by:
A = $$√3a^2/4$$​​
where a is the side length. Unlike scalene or right-angled triangles, an equilateral triangle has equal angles and sides, making it unique in geometry.