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\ 06-Jan-2025 Bharat Arora Proof-7 Reader’s Sign _______________________ Date __________
Learning by Doing
Objective: To prove the angle sum property for quadrilaterals.
Materials Required: A-4 sheets, geometry box, pencil, a pair of scissors
Procedure:
• On a sheet of paper, draw any quadrilateral PQRS as shown in figure.
P
Q
S
R
• Using a compass, draw four arcs of same radius at each vertex of the quadrilateral, that
is, P, Q, R and S as shown in the figure given below.
P
Q
S
R
• Now, colour all the four angles of the quadrilateral by using different colours.
• With the help of a scissors, cut out all the four angles along the arcs drawn in above step.
• Take another A4 sheet and paste all the cut outs of the angles obtained in above step.
Q
P
R
S
When the cut-outs of angles ∠P, ∠Q, ∠R, and ∠S are pasted in order, a circle is formed.
Thus, we can conclude that the sum of the angles at a point is equal to 360°.
∠P + ∠Q + ∠R + ∠S = 360°
Hence, the sum of interior angles of a quadrilateral is 360°.
Mathematics-8 86
