For a four bar linkage with r1 = 6in, r2 = 3 in, r3 = 4in, r4 = 4 in and initially in a non-crossed configuration (open),
a) find all the interior angles when θ1 = 25° and when θ2 = 170°.
b) reconsider using a vector based approach to find the angles of links 3 and 4 relative to the horizontal when θ2 = 45°.