I'm attempting to create a pentagon from 3/4in-thick pine boards, which will become part of a slightly odd shelving unit. Of the five angles, two are 90 degrees and I'm planning to use dowels and glue to connect them. The remaining angles are between 110 and 140 degrees, and I'm looking for some advice how to best join them.

Just glue? At those angles, I'm not sure the dowels will do much.

Also, any suggestions how to fixate the parts while the glue is solidifying?