# Worksheet on Triangle

In the worksheet on triangle we will solve 12 different types of questions.

1. Take three non - collinear points L, M, N. Join LM, MN and NL. What figure do you get?

Name:

(a)The side opposite to ∠L.

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(b) The angle opposite to side LN.

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(c) The vertex opposite to side MN.

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(d) The side opposite to angle N.

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2. Classify the triangle into acute triangle, obtuse triangle and right triangle with the following angles:

(a) 90°, 45°, 45°

(b) 60°, 60°, 60°

(c) 80°, 60°, 40°

(d) 130°, 40°, 10°

(e) 90°, 35°, 55°

(f) 92°, 38°, 50°

3. Classify the triangle according to sides, that is, equilateral, isosceles and scalene triangles

(a) 6 cm, 3 cm, 5cm.

(b) 6 cm, 6 cm, 6 cm.

(c) 7 cm, 7 cm, 5 cm.

(d) 8 cm, 12 cm, 10 cm.

(e) 3 cm, 4 cm, 5 cm.

(f) 3.5 cm, 3.5 cm, 4.5 cm.

4. Is it possible to have a triangle with the following angles and sides? Give reason in support of your answer.

(a) 110°, 60°, 30°

(b) 70°, 70°, 70°

(c) 80°, 35°, 65°

(d) 7 cm, 3 cm, 4 cm.

(e) 50°, 50°, 90°

(f) 10 cm, 12 cm, 2 cm.



5. Find the perimeter of a triangle when its sides are:

(a) AB = 7.6 cm, BC = 4.5 cm, CA = 6.3 cm.

(b) PQ = 4.00, QR = 3 cm, RP = 5 cm.

(c) LM = 4.5 cm, MN = 3.6 cm, NL = 6.2 cm.

6. If in a triangle LMN:

(a) ∠L = 80°, ∠M = 50°, find ∠N,

(b) ∠M = 60°, ∠N = 60°, find ∠L,

(c) ∠M = 100°, ∠ N = 30°, find ∠ L,

(d) ∠N = 90°, ∠L = 45°, find ∠M.

Mention the kind of triangle also.

7. The angle of a triangle is in the ratio of 2: 3: 4. Find the measure of each angle of the triangle.

8. One of the two equal angles of an isosceles triangle measures 55°. Determine the other angles.

9. The perimeter of a triangle is 24 cm. Two of its sides are 8 cm and 9 cm. Find the length of its third side.

10. Each side of a ∆ is one third of its perimeter. What kind of triangle is this?

11. One of the acute angles of a right triangle is 48°. Find the other acute angle.

12. Say whether the following statements are true or false:

(a) All the angles of an isosceles triangle are equal.

(b) If one angle of a triangle is obtuse, the other two angles must be acute.

(c) A right triangle can be equilateral.

(d) Equiangular triangle has its three sides also equal.

(e) A triangle can have two obtuse angles.

Classification of Triangle.

Properties of Triangle.

Worksheet on Triangle.

To Construct a Triangle whose Three Sides are given.

To Construct a Triangle when Two of its Sides and the included Angles are given.

To Construct a Triangle when Two of its Angles and the included Side are given.

To Construct a Right Triangle when its Hypotenuse and One Side are given.

Worksheet on Construction of Triangles.