Math CentralQuandaries & Queries


Question from cody:

I have an octagon 3ft tall by 3ft wide. What are the lengths of the diagonal lines to the vertical and horizontal lines?

Hi Cody,

I'm going to assume you mean a regular octagon. Are you looking for the length of AB, the red line in the diagram?

If so, then since ABC is a right triangle you can use Pythagoras theorem. You know the length of CA is 3 feet so all that remains is to find the length of BC.

Look at the first diagram in my response to a previous question. The length of BC is W - 2b in that diagram.

Can you complete the problem from here?


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