algebra question

Question

There is a video on how to calculate the size of paper required to make any size rectangular box origami box and the formula was based on c being 29.5 ...

 

^{+ b2 = c2}

 

^{= 870.25 divide by 2 = 435.125 = 20.8}

 

I can't seem to understand how this figure (870.25 was arrived at).

 

Regards,

wab

 

 

Answer 1

Square 29.5 and you get 870.25.