Brake line is flared at 45 degrees when using inverted flare fittings like came on your car originally. If you are using steel brake line you will need to double flare it with the proper double flaring tool. If you use 304 stainless steel tubing you would still flare it at 45 degrees but it is not necessary to double flare it.
If you are using aluminum AN fittings you will need to flare the tubing at 37 degrees. JIC hydraulic fitings are also flared at 37 degrees. They both use a tube nut and sleeve instead of a single nut like inverted flare does.