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# i am stumped :(

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1. In a certain regular square pyramid, all of the edges have length \(12\). Find the volume of the pyramid. (No image for this one.)

2. Donatello starts with a marble cube of side length \(10.\) He then slices a pyramid off each corner, so that in the resulting polyhedron, all the edges have the same side length \(s.\) Find \(s.\)

Here's the image for #2: Thanks!

Apr 12, 2020

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1) the formula for the volume of a pyramid is length*width*height/3. We know the length and the width but we don't know the height. Since we know this is a regular pyramid, and we know all edges have the length of twelve, we can draw a triangle with the information we know

height^2 + (1/2*length)^2 = k^2(where k is the length from any corner to the tip of the pyramid.) know we plug in the information we know.

height^2 + 36 = 144

height^2 =108

height = 6 root 3.

so then we plug in those values in to the formula for a pyramid and get 12*12*6 root 3 /3

= 4*12*6root3

=48*6(sqrt108)

Apr 12, 2020