Triangles

CBSE Class 6 Mathematics- Chapter 4- Basic Geometrical Ideas. Triangles Notes with Examples- A triangle is a three-sided polygon. It is a polygon with the least numbers of side.

Triangles

 

A triangle is a three-sided polygon. It is the polygon with the least
number of sides.
It is denoted by the symbol ∆.

We see many triangle shaped objects in our daily life.

 

Example: Draw a rough sketch of a triangle ABC. Mark a point P in
its interior and a point Q in its exterior. Is the point A in its exterior
or in its interior?

                                                              

Point A is not in the interior or exterior of ∆ ABC as it is a vertex (a
point where two line segments meet).

 

Example:
a) Identify three triangles in the figure.
b) Write the names of seven angles.
c) Write the names of six line segments.
d) Which two triangles have ∠B as common?

                                                        

a) The three triangles are ∆ABC, ∆ABD and ∆ACD
b) The angles are ∠BAC, ∠BAD, ∠DAC, ∠ABD, ∠ACD, ∠ADB and
∠ADC.
c) The line segments are AB, BC, CA, BD, DC and AD.
d) ∆ABC and ∆ABD have ∠B as common.

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