 # Constructions Class 9 Notes: Chapter 11

Class 9 CBSE math notes are provided here to help students overcome the challenges in learning the concepts of constructions. The notes which contain detailed information can be used as a great reference tool for studying productively as well as completing revisions before the exams. Some of the topics that are covered in the construction chapter are;

• Definition of Construction.
• Carrying out some basic constructions and giving reasons as to why these constructions are valid.
• Constructions of a triangle.
• Practice Questions.

## What is Construction?

The construction which is an important part of geometry basically means drawing angles, shapes, and lines in perfection. Constructions are usually carried out using only a ruler, compass and a pencil. As such, in chapter 11 students learn about the steps of drawing the perfect geometrical figures.

### Basic Constructions

Construction 1: To construct a given angle. Construction 2: To construct the bisector of a given angle.  Construction 3: To construct the perpendicular bisector of a given line segment.

Steps of Construction Construction 4: To construct an angle of 60 degrees.  #### Construction of Triangles

When we talk about the construction of a triangle we usually do not need the dimension and angles. However, there are some key conditions that can be followed when creating a triangle. Some of the conditions are as follows; #### Important Questions:

• Construct an angle of 90 degrees and justify the construction.
• Construct a triangle PQR in which QR = 5cm, ∠Q = 60° and PR – PQ = 2cm.
• Construct a right triangle whose base is 10cm and the sum of its hypotenuse and another side is 15 cm.