Overview
Exercise 13.1
Exercise 13.2
Review Exercise
MCQ’s
In Unit 13 of Class 9th Math, we explore the essential concepts related to the sides and angles of triangles. Triangles are fundamental geometric shapes that play a crucial role in various fields, including architecture, engineering, and mathematics.
Sides of Triangles
A triangle consists of three sides, each of which contributes to its overall shape and properties. The lengths of these sides determine the type of triangle formed. Triangles can be classified based on their sides as follows:
- Equilateral Triangle: All three sides are equal in length, and consequently, all three angles are equal (each measuring 60 degrees).
- Isosceles Triangle: Two sides are of equal length, and the angles opposite these sides are equal.
- Scalene Triangle: All three sides are of different lengths, leading to three different angles.
Understanding the properties of the sides helps in various geometric calculations, including perimeter and area.
Angles of Triangles
In addition to sides, the angles of a triangle are critical in determining its classification and properties. The sum of the interior angles of any triangle is always 180 degrees. This principle is fundamental in solving problems related to triangles and can be applied in various real-world scenarios.
Triangles can also be categorized based on their angles:
- Acute Triangle: All three angles are less than 90 degrees.
- Right Triangle: One angle is exactly 90 degrees.
- Obtuse Triangle: One angle is greater than 90 degrees.