Question: 3-D Diagonal

Comment on 3-D Diagonal

Why did you assume that there's a right angle there? Are we meant to assume that if it isn't stated
greenlight-admin's picture

We're told that we have a RECTANGULAR box. So, there are 90-degree angles at each corner.


does this formula work for a cube? I would assume so because all squares are rectangles but not vice versa--and thus the same for the 3D form of the figures. However, the answer in the example given here ( ) says that the L W and H of a cube are 1, but the total distance between opposite points on the figure is sqrt(5). This, however, does not comply with the formula above. Can you please provide some clarity?
greenlight-admin's picture

Yes, the formula in the video will work for cubes as well.

NOTE: The formula finds the straight line distance (the shortest distance) between the opposite vertices.
That is, if a fly were to DIRECTLY travel from one vertex to the opposite vertex, we can use the formula to find that distance.

The question at is slightly different.

In that linked question, the ant doesn't travel the shortest distance from A to B. Instead, the ant walks from point A to point B along the OUTSIDE of the cube.

Does that help?


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