Perfect arc path in After Effects
You could do this with an expression, but the simplest way would probably be to just rotate around a point (Like if you attach a ball to a pole and swing around).
You could simply use the Anchor point tool to move the
Anchor point outside of the circle and animate 90 degrees of rotation, but if you want some actual precision, like if it should align with other objects precisely, you should probably do it with a
null object as the parent of the
circle and rotate the
null instead. That way you can align the
null with the
circle object pretty effortlessly
I made a null that I aligned with the circle and made the null parent to the circle. Then I animated the null with a 2 keyframe rotation animation from 0 degrees to -90.