CAT Introduction to Triangles - Practice Questions & MCQ

You have studied about triangles and their various properties in your earlier classes. You know that a closed figure formed by three intersecting lines is called a triangle. (‘Tri’ means ‘three’). A triangle has three sides, three angles and three vertices. For example, in triangle ABC, denoted as ∆ ABC; AB, BC, CA are the three sides, ∠ A, ∠ B, ∠ C are the three angles and A, B, C are three vertices.

Types of Triangle

Equilateral Triangle: A triangle having all sides equal is called an equilateral triangle.

Here, ABC is a triangle in which AB = BC = CA  is an equilateral triangle.

Isosceles Trianle: A triangle having two sides equal is called an isosceles triangle.

Here, ABC is a triangle in which AB = AC is an isosceles triangle.

Scalene Triangle: A triangle in which all the sides are of different lengths is called a scalene triangle.

Here, ABC is a triangle in which   is a scalene triangle.

Acute-angled triangle: A triangle in which every angle measures more than but less than is called an acute-angled triangle.

Here, ABC is a triangle in which every angle is an acute angle. is an acute-angled triangle.

Right Angled Triangle: A triangle in which one of the angles measures is called a right-angled triangle or simply a right triangle. In a right-angled triangle, the side opposite to the right angle is called its hypotenuse and the remaining two sides are called its legs.

In the given figure, is a right triangle in which , AC is the hypotenuse, and AB, BC are its legs.

Obtuse-angled triangle: A triangle in which one of the angles measures more than but less than is called an obtuse-angled triangle.

Here, ABC is a triangle in which is an obtuse angle. is an obtuse-angled triangle.