+28 If a vector has direction of 230degrees from the positive x axis, what are the signs of its x and y components? If the ratio Ry/Rx is negative, what are the possible angles for R as measured from the positive x axis?
+39 Convention in maths is to measure an angle, from the positive x-axis, in the counter-clockwise direction.
Which means that 90 degrees points up, or in the positive y-direction, 180 degrees would be pointing left (-x) and 270 degrees would be pointing down (-y).
Anywhere between 0 and 180 degrees means the vector has a positive y-component.
Anywhere between 0-90 and 270-360 degrees means the vector has a positive x-component.
In this case the vector has neither a positive x-component nor a positive y-component.
Were you to draw it, you find it points down and to the left.
So both the x and y signs are negative (-).
If your y/x ratio is negative then the signs are not equal. That means you cannot have a positive x and positive y and you cannot have both negative x and y.
The corresponding angle for positive x and y is 0-90 degrees and for negative x and y it is 180-270 degrees.
That means the possible angles are 90-180 and 270-0 degrees.
