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

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Question 1205296: A right pyramid on a square base of side 4cm 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 square base of side 4cm has a slant edge of 6cm.
Calculate the volume of the pyramid
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We are given that the side of the square base is 4 cm.
 
Then the diagonal of the square is 4%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  2%2Asqrt%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-%282%2Asqrt%282%29%29%5E2%29 = sqrt%2836-8%29 = sqrt%2828%29  cm.


Thus the volume of the pyramide is 

    %281%2F3%29%2Abase_area%2Ah = %281%2F3%29%2A4%5E2%2Asqrt%2828%29 = %2816%2F3%29%2Asqrt%2828%29 = = %2832%2F3%29%2Asqrt%287%29 = 28.221 cm^3  (approximately).    ANSWER

Solved.