hello,
I have a big problem.
I Study at electronica area and the teacher asked to make two graphs of this kind:

http://www.eletronica24h.com.br/Curs...s2/A8Fig04.gif

is there any formula I can use the graph curves are like that? someone has a graphic of this kind you can send me? Does anyone have or tell me where I can download and exchange data only?
Sorry for my bad English

PLEASE HELP ME

best regards
FRANKY