Answer 1

Radius (r) = 5 cm

𝜃 = angle subtended at centre (degrees)

Length of Arc =`theta/360^@`× 2𝜋r cm

But arc length =`5pi/3`𝑐𝑚

`theta/360^@× 2pi × 5 =(5pi)/3`

`theta=(360^@×pi)/(3×2pi)= 60^@`

∴ Angle subtended at centre = 60°