Question

In a certain machine, the crank OA of the four-bar linkage (all rigid) shown below is driven at a constant counterclockwise angular velocity w0 = 12 rad/s.

i need to find a relation between those bars to find wab and wbc , i have found the relative velocites relations for them but i still need the relation between the angels to analyse Rab components and Rbc components i need to solve this in geometry because i will then convert the solution to a matlap programm