Find the direction angle of the vector v. Recall that the direction angle is the angle measured in the anti-clockwise direction from the positive x-axis to the vector u. Also recall that the direction angle for a vector u = ai + bj is determined from tan = b a . Therefore, the direction angle of the vector v = 9(cos 140i + sin 140j) is tan . Recall the relationship between sin, cos, and tan, which states that tan = sin cos