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Which equations represents circles that have a diameter of 12 units and a center that lies on the y-axis? check all that apply

What is the measure of the smallest angle in the diagram? 15 29 32 45

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).