Wikipedia:Reference desk/Archives/Mathematics/2008 June 22

= June 22 =

Brahmagupta's formula
Brahmagupta has a "Reference diagram" marked ABCDpqrs and text using abcd and s. I think abcd are really pqrs and the text s is something else. Could someone please explain what the text all means - I find it unclear - and better yet edit the article or diagram to make them match. -- SGBailey (talk) 09:37, 22 June 2008 (UTC)
 * S is half the sum of the sides and I think the picture should be replaced with one that shows the lengths of the sides as a, b, c and d. So, in the text, the lowercase variables are the lengths of the four sides which are shown as p, q, r and s in the picture. Zain Ebrahim (talk) 09:43, 22 June 2008 (UTC)
 * It's easier to edit the text, so I've done that. —Ilmari Karonen (talk) 11:25, 22 June 2008 (UTC)

Carrying on down to the next figure we have "root(ac+bd)" without abcd being defined. I think these are some of pqrs in the diagram above, but which is which. Should this be changed to "root((AB)(CD)+(BC)(AD))"? -- SGBailey (talk) 13:48, 22 June 2008 (UTC)