Q3 of 35 Page 193

The lateral faces of a square pyramid are equilateral triangles and the length of a base edge is 30 centimetres. What is its surface area?

Given lateral faces of square pyramid is equilateral triangle

side = 30cm


Since it is a equilateral triangle


lateral Base (b) = 30 cm


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


= 30 × 30


Area of a square base (A) = 900 cm2




Area of an equilateral triangle = 225√3 cm2


Area of an 4 equilateral triangle = 4× 225√3 = 900√3 cm2


Total surface area = 900 + 900√3 = 900(1 + √3)cm2


More from this chapter

All 35 →
1

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?

 2

A toy is in the shape of a square pyramid of base edge 16 centimetres and slant height 10 centimetres. What is the total cost of painting 500 such toys, a 80 rupees per square metre?

 4

The perimeter of the base of square pyramid is 40 centimetres and the total length of all its edges is 92 centimetres. Calculate its surface area.

 5

Can we make a square pyramid with the lateral surface area equal to the base area?