What angle does an arc of 10cm subtend at the centre of a circle of radius 10cm? Give the answer to the nearest 0.1

Answer 1

simple way:
arc-length = rθ , where θ is the sector angle in radians
10 = 10θ
θ = 1 radian

detailed solution:
circumference of whole circle = 2π(10) = 20π cm
so by ratios
sector arc : circumference = sector angle : whole rotation
10/20π = θ/2π
1/2 = θ/2
θ = 1