Question

Find the direction angle of the vector v = -5i - 8j. That is, find the angle between 0 degree and 360 degree that v makes with the positive x-axis (measured counterclockwise), when v is in standard position.Do not round any Intermediate computations, and round your answer to the nearest whole number.

Answer 1

To calculate this angle theta we use the arctan function. But this function only gives the value between

`-(\pi)/(2)<\theta<(\pi)/(2)`

Then

`\theta=180+\tan ^(-1)(-8)/(-5)=237.9946167919165`

So, the angle is 238°.