Class 6 Maths Basic Geometrical Ideas Triangles


A three-sided polygon is termed as a triangle. Below is the image of a triangle ABC.

A triangle is denoted by △

Triangle has three sides (line segments) AB, BC, CA

Triangle has three angles, ∠ACB, ∠CAB, ∠ABC

Triangle has three vertices, A, B, C

Triangle being a closed curve, has three regions; interior, exterior and boundary.


Question: In the given figure:

  • Identify three triangles in the figure
  • Write the names of seven angles
  • Write the names of six-line segment
  • Which two triangles has ∠B as common.


△ ABC, △ ABD and △ ADC

∠ABD, ∠ADB, ∠BAD, ∠ADC, ∠DAC, ∠DCA and ∠BAC

AB, AD, BD, AC, DC and BC

△ ABC and △ ABD has ∠B as common.

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