Circles- arcs and sectors

Question 1

How do we find the arc length?

Answer 1

Calculate the full circumference C = πd.

Find the required fraction of the circumference.

Question 2

How do we find the area of a sector?

Answer 2

Calculate the area of the whole circle :- A = π r(squared)

Calculate the required fraction.

Question 3

How do we find the angle at the centre given the arc length?

Answer 3

Angle (x°) = arc length divided by circumference x 360°

Question 4

How do we find the angle at the centre given the area?

Answer 4

Angle = area of sector divided by area of circle x 360°