Points A and B are separated by a lake. To find the distance between them, a surveyor locates a point C on land such than ∠ C A B = 46.9 ° . Find the distance across the lake from A to B.

Amass weighing 16 pounds stretches a spring 8/3 feet. the mass is initially released from rest from a point 2 feet below the equilibrium position, and the subsequent motion takes place in a medium that offers a damping force that is numerically equal to 1/2 the instantaneous velocity. find the equation of motion if the mass is driven by an external force equal to f(t)=cos(2t).