In a circle O, draw chord AB such that AB = r (r is the radius) find the length of theminor arc AB.

(Tried drawing it, and it ended up having a 90 angle but it didn’t work. What do i do?)

you need a compass to do it right. Pick a point A on the circle.

Set the compass to reach to the center, then use that radius to mark where the arc intersects the circle at B.

Since all 3 sides of the triangle are the same, the angle is pi/3.
The arc s = pi/3 * r