class VII(sum of interior angles of a triangle)

Objective: To find the relationship between the interior angles of a triangle by paper cutting and pasting.

Material required:coloured paper, glue, a pair of scissors, and pencil.
Procedure:
step 1: On a coloured paper, draw any triangle and name its vertices as A, B and C.


Step 2: Label the interior angles as angle ABC, angle BCA and angleCAB.

Step 3: Cut triangle ABC.
Step 4:Cut the three angles.
Step 5: Draw a straight line on a sheet of paper.

Step 6: Place the three interior angles angleBAC , angleABC and angleACB on the straight line, adjacent to each other, without leaving any gap.



Result: angleABC + angleBCA + angleCAB = 180 degrees.