Question

A triangle with all 3 equal sides is called as :
A. isosceles
B. equilateral
C. scalene
D. none of these

Answer 1

Hint: As on the basis of properties and sides a triangle has, we have three types of triangle. Before giving an answer to this question first we will discuss the properties of all three triangles, which helps us to reach our answer. We will discuss isosceles, equilateral and scalene triangles one by one.

Complete step by step answer:
As we know that based on the length of a triangle’s sides there are three types of triangle; isosceles triangle, equilateral triangle and scalene triangle.
First let’s start with the isosceles triangle. An isosceles triangle has two equal sides and one unequal side. Also, the opposite angles to the equal sides are also equal.

Now, let’s discuss the equilateral triangle. All sides of an equilateral triangle are equal in length. Also, all angles are equal so it is also called an equiangular triangle. All angles of an equilateral triangle measures $60{}^{\circ }$.

Now we will discuss the scalene triangle. The Scalene triangle has all sides of unequal length. As the length of sides is not equal so the angles are also unequal.

When we read all the properties of these three triangles we get our answer. A triangle with all 3 equal sides is called an equilateral triangle.

So, the correct answer is “Option B”.

Note: A triangle is a two-dimensional shape having three sides, three vertices and three angles. The sum of all interior angles of a triangle is always $180{}^{\circ }$ either it is isosceles, equilateral or scalene triangle. Also, a fact is that no triangle has more than two right angles (i.e. $90{}^{\circ }$) because it won’t make a triangle.