Properties And Construction Of Tringle Samralab

Govt. Sen. Sec. School,Samrala (Boys) Project of Properties and Construction of Triangle Made by: Mrinaal

7th B

Taranjeet Singh

7th B

Kuldeep Singh

7th B

Yasandeep Singh 7th B

Guided By: Mrs. Jaspreet Kaur (Math Mistress) Ms. Anjali Manro (CF)

Source of Information: PSEB Text book of class 6th ,7th

Properties and Constructions of Triangle.

Definition of Triangle

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A triangle is a closed figure joining of three non– collinear points. ∆ is used to denote triangle

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Points A,B,C, are vertices.

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A triangle has six parts: three angles and three sides.

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Classification of triangle 1. Classification of 2. Classification of triangles based triangles based on sideson angles II. Equilateral ii. Acute angled triangle triangle III. Isosceles triangle iii. Right angled triangle IV. Scalene triangle iv. Obtuse angled triangle

Classification of Triangle based on sides Types of triangle

Explanation

1. Equilateral triangle

A triangle having three sides equal is called equilateral triangle. i.e. AB= BC=CA

2. Isosceles triangle

A triangle with any two sides equal is called isosceles triangle. i.e. AB=AC

3. Scalene triangle

A triangle whose all sides have different length is called scalene triangle. AB ≠BC≠CA

Diagram

Classification of Triangle based on angles Types of triangle

Explanation

Acute angled triangle

A triangle whose all angles are acute (i.e. between 0° to 90°) is called acute angled triangle.

Right angled triangle

A triangle whose one angle is right angled (i.e. 90°) is called right angled triangle.

Obtuse angled triangle

A triangle whose one angle is obtuse (i.e. between 90° to 180°) is called obtuse angled triangle.

Diagram

Properties of Triangle

3. The sum of any two sides of a triangle is greater than third side AB + BC > AC or BC + CA > AB or CA + AB > BC

Construction of Triangles To construct a triangle when two sides and angle between them is given. or To construct SAS triangle.

Steps of Construction 1. Draw PR = 5 cm 2. With the help of D, draw an angle YPR = 70° 3. Cut line segment PQ=3 cm from ray PY. 4. Join QR. . . . PQR is required triangle

To construct a triangle when two angles and the side between them is given. i.e. To construct ASA triangle.

Steps of construction

To construct a triangle whose all sides are given i.e. To construct SSS triangle.

Given-

A triangle with sides 5c.m, 4c.m, and 2.5c.m. To construct- Draw a rough figure of triangle with given sides

Steps of construction 1. Draw BC = 5c.m 2. With B as centre, make an arc taking 4c.m as radius 3. With C as centre, again make an are 2.5c.m as radius which cuts first at A. 4.Join A to B and C ∆ ABC is required triangle.

Steps of construction 1. Draw EF= 3.8c.m

3. With F as centre, make an arc of length 4.2c.m which cuts EX at D. 4. Join DF . . . ∆DEF is required triangle.

To construct a right angled triangle when hypotenuse and one side is given