The arc length formula is Arc Length = Radian Angle x Arc Radius or Arc Length = (Degree Angle/360) x 2π x Arc Radius, depending on whether you're measuring in radians or degrees. That said ...

In order to derive the formula to calculate the angle at the centre of the sector, the formulae for the arc length and area of ... 17^\circ\) (to the nearest degree) Now try the example question ...