triangle / class 1-2-3 / Knowledge Hub

Knowledge hub Published on: March 19, 2021

What is triangle?

Ans:- A closed figure that is bounded by three sides is called triangle.

Three sides = AB , BC , AC

Three angles = ㄥBAC , ㄥABC , ㄥACB

Three Vertex = A , B , C

How many types of triangle on the basis of side?

Ans:- There are three types of triangle on the basis of side.

1- Equilateral triangle

2- Isosceles triangle

3- Scalene triangle

What is equilateral triangle?

Ans:- A triangle whose all three sides are equal is called equilateral triangle.

What is isosceles triangle?

Ans:- A triangle whose two sides are equal is called isosceles triangle.

What is scalene triangle?

Ans:- A triangle whose no any sides are equal is called scalene triangle.

How many types of triangle on the basis of angle?

Ans:- There are three types of triangle on the basis of angle.

1- acute angled triangle

2- obtuse angled triangle

3- right angled triangle

What is acute angled triangle?

Ans:- A triangle whose all three angles are less than 90° is called acute angled triangle.

What is obtuse angled triangle?

Ans:- A triangle whose one angle is greater than 90° and two other angles are less than 90° is called obtuse angled triangle.

What is right angled triangle?

Ans:- A triangle whose one angle is 90° and two other angles are less than 90° is called right angled triangle.

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problem type - 2

problem type -3

problem type -4

problem type -5

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problem type -9

1- A triangle has _________ sides.

2- A triangle has _________ angles.

3- A triangle has _________ vertices.

problem type -10

1- In △ ABC if ∠A = 45° , ∠B = 65° then find ∠C

2- In △ ABC if ∠BAC = 120° , ∠ABC = 30° then find ∠BCA

3- In △ ABC if ∠A = ∠C = 75° then find ∠B

4- In △ ABC if ∠A = ∠B and ∠C = 90° then find ∠A and ∠B

5- In △ ABC if ∠A =∠B = ∠C then find the angles of the triangle

6- Find the measure of the angles of a triangle if all the angles are equal.

problem type -11

In which of the following cases is a triangle possible with the given group of angles?

a- 90° , 60° , 30°

b- 77° , 84° , 20°

c- 59° , 60° , 61°

d- 135° , 22° , 22°

e- 73° , 73° , 33°

f- 54° , 72° , 54°

problem type -12

In which of the following cases is the construction of a triangle ABC possible.

1. AB = 3cm , BC =4cm , CA = 1cm

2. AB = 5cm , BC =7cm , CA = 8cm

3. AB = 9cm , BC =4cm , CA = 3cm

4. AB = 10cm , BC =7cm , CA = 8cm

problem type -13

1. Construct a triangle ABC in which BC = 7cm , AC = 5cm , and AB = 3cm

2. Construct a triangle ABC in which AB = 2cm , AC = 5cm , and BC = 3cm

3. Construct a triangle PQR in which PQ = 4.8cm , PR = 7cm , and QR = 4.5cm

4. Construct a triangle ABC for which a = 7cm , b = 6cm , c = 5cm

5. Construct a triangle ABC in which BC =5.5cm , AB = CA = 7.5cm

6. Construct a triangle ABC in which BC = 4cm , AB = CA = 3cm

7. Construct an equilateral triangle ABC each of whose sides = 5.7 cm

8. Construct an equilateral triangle ABC each of whose sides = 3cm

9. Construct a triangle PQR in which ∠Q = 60°, QR = 6cm and PQ = 5cm.

10. Construct a right angled triangle ABC in which ∠B = 90° , BC = 5cm and AB = 4cm