Question

Which of the following is a regular polygon?
A). Any triangle
B). Equilateral triangle
C). Isosceles triangle
D). None of these

Answer 1

Hint: These types of questions which are based on the geometrical shape can be answered if you know about the geometrical structure such as how they are formed, what angles are formed in a regular polygon which sides of regular polygons are equal this information can help you to have a better approach towards the solution.

Complete step-by-step solution -
A polygon is a two-dimensional enclosed figure made by joining 3 or more straight lines. They are also known as “flat figures”. A polygon having equal sides of equal lengths are called regular polygons. A regular polygon is a polygon that is equiangular i.e. All the angles are equal in measure and equilateral i.e. all sides have the same length.

We know that the equilateral triangle is a regular triangle whose internal angle is ${60^ \circ }$ and its sides are also the same (equal length).

Whereas, an isosceles triangle is defined as the triangle with two sides equal in length to each other while the third side which is a base can have any length possible. Therefore, we can conclude that for an isosceles to be a regular polygon, it needs the base to also have the same value to its other two sides and the angles are of the same measure. Only in this condition, we can say an isosceles triangle is a regular polygon. Similarly, it goes for other different triangles. Thus, according to the question, the answer should be an equilateral triangle as it fulfills all the conditions to be a regular triangle.
Hence, option B is correct.

Note: In the options given option A is cannot be the regular polygon because we know that not every triangle have an angle of ${60^ \circ }$ and equal sides also in an isosceles triangle the two sides are equal to each other which results in two equal angles but in a regular polygon every side and every angle are equal to each other thus option C was not a correct option.