I am helping my dad build a sunroom onto our house this summer. It will be rectangular, with floor dimensions of 16'0" x 9'4".

He has challenged me to figure the exact length between opposite corners on the floor using geometry instead of a tape measure. I have forgotten how to do this.

Can anybody help?

"The square of the hypotenuse is equal to the sum of the squares of the other two sides" is the phrase you had right on the tip of your tongue. Converting the dimensions to inches, your sunroom is (16x12=)192" by ([9x12]+4=)112".

Square those numbers: 192x192= 36,864.00"
112x112= 12,544.00"

Add them together and you get 49,408.00", which is the square of the hypotenuse--the side across from the right angle. Take the square root of this number, using your dad's slide rule, and you get 222.279103831"--or just over 18'6".

I think...

[This message was edited by dmmcwethy on 06-12-02 at 08:44 AM.]

Actually you can use the old Pythgrean Therom that is a^2+b^2=c^2 !