# Ex 11.1, 5 - Chapter 11 Class 9 Constructions

Last updated at Oct. 5, 2018 by Teachoo

Last updated at Oct. 5, 2018 by Teachoo

Transcript

Ex 11.1, 5 Construct an equilateral triangle, given its side and justify the construction. Let equilateral triangle be ABC Draw AB = 5 cm Taking A and B as centers, radius = AB = 5 cm, draw two two arcs intersecting each other at A Join AB and AC Thus Δ ABC is our required triangle Ex 11.1, 5 Construct an equilateral triangle, given its side and justify the construction. Let’s assume side of equilateral triangle is 5.5 cm In an equilateral triangle, all sides are equal So, our triangle looks like Let’s construct it Steps of construction 1. Draw a line segment AB of length 5.5 cm 2. Taking 5.5 cm as radius, and A as center, draw an arc. 3. Taking 5.5 cm as radius, and B as center, draw another arc. 3. Taking 5.5 cm as radius, and B as center, draw another arc. Thus, Δ ABC is the required equilateral triangle Justification By construction, AB = AC = BC Since all sides are equal ∴ ∆ABC is an equilateral triangle. Thus, the Construction is justified.

Constructing bisector of angle and perpendicular bisector

Chapter 11 Class 9 Constructions

Concept wise

- Constructing bisector of angle and perpendicular bisector
- Constructing angles - 60, 90, 45, 30 and others
- Constructing Triangle - Given base, angle and sum of other 2 sides
- Constructing Triangle - Given base, angle and difference of sides
- Constructing Triangle - Given sum of 3 sides and 2 base angles

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.