Q4 of 35 Page 197

All edges of a square pyramid are 18 centimetres. What is its volume?


LH = Height of pyramid


HG = Half of a diagonal


BC = base edge = 18cm


LG = lateral edge = 18cm


BG = Full diagonal = √(182+ 182) = 18√2 cm



By Pythagoras theorem


HL = √(LG2 – HG2)


= √(182 – (9√2)2)


= √(324 – 162)


= √162 cm


We know that,


Volume of a pyramid


Volume of a pyramid



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