Page 107 - Start Up Mathematics_8 (Non CCE)

MATHS LAB ACTIVITY

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Objective: To verify the identity (a – b) = a – 2ab + b a
by cutting and pasting I
Material required: Ruler, pencil, a pair of scissors, white
sheet of paper, coloured sheets of paper (5 to 6 different
colours), glue stick/fevicol
Method: Start with the RHS of the identity. Purple colour 10 cm
Step 1: Take a coloured sheet of paper (say purple) and
cut a square of side a cm. Let a be 10 cm. Mark
this square as I.
Step 2: Now cut a square of side b cm from the second
sheet of coloured paper (say blue). Let b be 4 cm.
Mark this square as II. 10 cm

b
II

Blue colour 4 cm

4 cm

Step 3: Cut two rectangles from the third sheet of coloured paper (say pink) of dimensions
(a – b) ¥ b cm.

a – b a – b
III IV

b Pink colour 4 cm b Pink colour 4 cm

6 cm 6 cm
Step 4: Paste square I on the white sheet of paper.
Step 5: Then paste square II and the rectangles III and IV on square I as shown.

Paste along IT, TN, ON, OG and GK. Do not paste other portions of II, III and IV.

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