In a circle of diameter 40 cm, the length of a chord is 20 cm. Find the length of minor arc of the chord.
Diameter of the circle =40 cm
∴ Radius (r) of the circle =402=20 cm
Let AB be a chord (length = 20 cm) of the circle.
In △OAB, OA = OB = Radius of circle = 20 cm
Also, AB = 20 cm
Thus, △OAB is an equilateral triangle.
∴θ=60∘=π3 radian
We
know that in a circle of radius r unit, if an arc of length I unit
subtends an angle θ radian at the centre, then
θ=lr
∴π3=arc AB20⟹arc AB=203π cm