### Mathematics Class VII

Integers
Fractions and Decimals
Exponents and Powers
Algebraic Equations
Simple Linear Equations
Lines and Angles
Comparing Quantities
Congruence of Triangles
Rational Numbers
Perimeter and Area
Data Handling
Practical Geometry
Symmetry
Visualising Solid Shapes

# Construction Of Triangles

The construction of triangles is based on the rules of congruent triangles. A triangle can be drawn if-

• Three sides are given (SSS criterion).
• Two sides and an included angle are given (SAS criterion).
• Two angles and an included side are given. (ASA criterion).
• A hypotenuse and a side are given for right angle triangle (RHS criterion).

Construction of a triangle with three given sides (SSS criterion)

Example

Draw a triangle ABC with the sides AB = 6 cm, BC = 5 cm and AC = 9 cm.

Solution

Step 1: First of all draw a rough sketch of a triangle, so that we can understand how to go ahead.

Step 2: Draw a line segment AB = 6 cm.

Step 3: From point A, C is 9 cm away so take A as a centre and draw an arc of 9 cm.

Step 4: From point B, C is 5 cm away so take B as centre and draw an arc of 5 cm in such a way that both the arcs intersect with each other.

ABC is the required triangle.

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