Answer1


2 comments:

Benjamin Leis said...

This comes directly from Ptolemy's Theorem as well:

EO * CD = CE * DO + DE * CO or

EO = (CE * DO + DE * CO ) / CD

CD = sqrt(a^2 + b^2)
CO = DO = CD * sqrt(2) / 2

So EO = (b * CD * sqrt(2) / 2 + a * CD * sqrt(2) / 2) / CD
= (a + b) * (CD * sqrt(2) / 2 ) / CD
= (a + b) * sqrt(2) / 2

Benjamin Leis said...

I left off ECOD is a cyclic quad due to the two opposing right angles E and O.