The rule for a rotation by 90° about the origin is (x,y)→(−y,x) .

What is 90 degrees in an angle?

Angles that are 90 degrees (θ = 90°) are right angles. Angles that are 180 degrees (θ = 180°) are known as straight angles.

Which direction is 90 degrees anticlockwise to the direction opposite to that?

Hence, north-east is 90° anti-clockwise to the direction opposite to that of north-west.

How do you rotate a vector 90 degrees?

Normally rotating vectors involves matrix math, but there’s a really simple trick for rotating a 2D vector by 90° clockwise: just multiply the X part of the vector by -1, and then swap X and Y values.