Page 233 - ICSE Math 7

6. Construct a ∆ ABC in which AB = 6 cm, AC = 6.5 cm and ∠BAC = 60º.
7. Construct a ∆ PQR in which PQ = 5.2 cm, PR = 6.0 cm and ∠QPR = 45º.
8. Construct a triangle ABC in which AB = 6.2 cm and ∠A = ∠B = 75º.
9. Construct a triangle ABC in which BC = 6.5 cm, ∠C = 45º and ∠B = 60º.
10. Construct a right-angled triangle having hypotenuse 7 cm and one of its acute angles measuring 45º.

Maths Lab Activity

Objective: Construction of an equilateral triangle by
paper folding

Step 1: Take a rectangular paper with base AB.

A B

Step 2: Fold the paper vertically into 2 halves to obtain
the perpendicular bisector through the midpoint
D of the width AB. Press to form the crease and
then unfold it.

A D B
Step 3: Next, make a fold so that the corner point B

falls on the perpendicular bisector. Press it when
the fold passes through A. B
E

Step 4: Make another fold along AB (as shown) so that
the vertical length along A coincides with AE. A A

Press it to form a crease.

Step 5: Unfold the paper and mark the point C as shown. C C

Step 6: Finally, either fold or join BC to obtain an
equilateral ∆ ABC. A D B A D B

Justification:

Can you justify why ∆ ABC is equilateral?
[Hint: Since AB coincides with AC (as B lies on C),

∴ AB = AC and D ADC ≅ D BDC (why?)

Hence, AC = BC.]

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