Please refer the attached part.

Sketched Bend 4 feature has Bend radius 0.433mm, Arc length 0.816mm, Bend Angle 90degrees

I tried to find a formula that will return arc length. but couldn't do it.

Can someone suggest what the calculation should be?

Question: Given Bend arc radius & angle, calculate arc length. (Radius = r, angle = theta)

r * theta = arc length doesn't work here.