Q1 of 35 Page 193

A square of side 5 centimetres, and four isosceles triangles of base 5 centimetres and height 8 centimetres, are to be put together to make a square pyramid. How many square centimeters of paper is needed?

Given: side of a square = 5cm

There are 4 isosceles triangle


Base (b) = 5cm


Height (h) = 8cm


Area of a square base (A) = side × side


= 5 × 5


Area of a square base (A) = 25 cm2


Area of one isosceles triangle



Area of one isosceles triangle = 20cm2


Area of 4 isosceles triangle = 4 × 20 = 80cm2


Total surface area = 25 + 80 = 105cm2


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