SOLUTION: A right pyramid on a base of 4cm square has a slant edge of 6cm. Calculate the volume of the pyramid

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Question 1205291: A right pyramid on a base of 4cm square has a slant edge of 6cm. Calculate the volume of the pyramid
Answer by ikleyn(52835) About Me  (Show Source):
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A right pyramid on a base of 4cm square has a slant edge of 6cm.
Calculate the volume of the pyramid
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I believe that the pyramid is REGULAR, which means that its base is a square.


If so, then the side of this square is sqrt%284%29 = 2 cm,
 
and the diagonal of the square is 2%2Asqrt%282%29 cm.



Draw the height (the altitude) of the pyramid from the upper vertex to the base of the pyramid.


You will get a right-angled triangle with one leg on the base as the half
of the diagonal of the square, so the length of this leg is  sqrt%282%29 cm long.


The hypotenuse of this right-angled triangle is 6 cm (it is the slant edge).


Hence, by Pythagoras, the altitude is  h = sqrt%286%5E2-%28sqrt%282%29%29%5E2%29 = sqrt%2836-2%29 = sqrt%2834%29  cm.


Thus the volume of the pyramide is 

    %281%2F3%29%2Abase_area%2Ah = %281%2F3%29%2A4%2Asqrt%2834%29 = %284%2F3%29%2Asqrt%2834%29 = 7.7746 cm^3  (approximately).    ANSWER

Solved.