Knowing & Measuring Triangles

Mensuration on Triangles

A triangle is a closed figure formed by three line segments.  It has three vertices, three sides and three angles. 

In any triangle drawn by joining three non-collinear points, the sum of the lengths of any two sides is greater than the length of the third side. This property is called as Triangle inequality.  

Few important points about triangles:

1. Triangle is formed by joining three ______________ points.

2. A triangle has ______________ vertices and ______________ sides.

3. A point where two sides of a triangle meet is known as ________ of a triangle.

4. Each angle of an equilateral triangle is of ______________ measure.

5. A triangle has angle measurements of 29°, 65° and 86°. Then it is _______ triangle.

(i) an acute angled                   (ii) a right angled
(iii) an obtuse angled               (iv) a scalene

6. A triangle has angle measurements of 30°, 30° and 120°. Then it is _______ triangle.

(i) an acute angled                   (ii) scalene
(iii) obtuse angled                   (iv) right angled

7. Which of the following can be the sides of a triangle?

(i) 5,9,14          (ii) 7,7,15         (iii) 1, 2, 4        (iv) 3, 6, 8

8. Ezhil wants to fence his triangular garden. If two of the sides measure 8 feet and 14 feet then the length of the third side is __________

(i) 11 ft            (ii) 6 ft             (iii) 5 ft            (iv) 22 ft

9. Can we have more than one right angle in a triangle?

10. How many obtuse angles are possible in a triangle?

11. In a right triangle, what will be the sum of other two angles?

12. Is it possible to form an isosceles right angled triangle? Explain.

Test Your Knowledge on Triangles