4. A force of 800 N acts downward at A on the mechanism, which is pinned at B, has a roller at D, and is attached to a spring with a force constant of 6 kN/m. The spring is unstretched when = 0. All members are joined by frictionless pins. Calculate at equilibrium. answer: 41.3° B. wwwwwww 1 m k = 6 kN/m 1 m 800 N 1 m