ok i have no idea how to do this, can you guys please help me out with this for physics?

"For no apparent reason, a poodle is running counter-clockwise at a constant speed of 3.90 m/s in a circle with radius 2.3 m. Let v_1 be the velocity vector at time t_1, and let v_2 be the velocity vector at time t_2. Recall that average acceleration = delta_v/delta_t."

i really need help on finding the magnitude and direction of the average acceleration at a given delta_t, for example, delta_t=0.5

i've used the formulas v_x=-w sin wt and v_y = w cos wt, but i'm not sure if that's right. anyways, thanks in advance to anyone who helps