how to calculate arc of the circle

3 answers

Assistance needed.
in general
arclength = radius * theta, where theta is the sector angle measured in radians.
BUT, since this is labeled grade 8, I doubt if you have studied radian measure.

So, the other way would be to calculate the circumference of your circle first.
Then you would have to know the sector angle.
set up the proportion

arc/circumference = sector angle/360º

eg. if the radius is 10 cm and the angle is 40º
arc/20pi = 40/360
arc = 80pi/360 = ....
when & when