The angle vector 'a' makes with the positive x-axis is 90° to 180°.
A vector is a quantity that has magnitude as well as direction one such example of this is velocity where we describe speed and direction also.
Given a vector a with two components one in the x direction and another one in the y direction.
The x component of the vector ax < 0 which is on the 2nd quadrant and the y component of the vector is ay > 0 which we join to the tail of the component ax.
∴ The angle it makes with the positive x-axis is 90° to 180° as it is on the second quadrant.
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