Four-bar linkage analysis: 4R quadrilateral
The four-bar linkage is a basic machine component. It comes in two primary forms the 4R quadridlateral and the slider-crank. Here are my notes for the analysis of the 4R quadrilateral.
http://synthetica.eng.uci.edu/~mccarthy/mechanicaldesign101/McCarthyNotes-2.pdf
Four-bar linkage analysis