The straight metal arm of a windscreen wiper on a car rotates in a circular motion from a pivot point, O, through an angle of 140°. The windscreen is cleared by a rubber blade of length 46 cm that is attached to the metal arm between points A and The total length of the metal arm, OB, is 56 cm. The part of the windscreen cleared by the rubber blade is shown unshaded in the following diagram.

attempt to substitute into length of arc formula $\frac{140^\circ}{360^\circ} \times 2\pi \times 56$ (M1) $137 \text{ cm} (136.833\ldots, \frac{392\pi}{9} \text{ cm})$ (A1)

subtracting two substituted area of sectors formulae (M1) $(\frac{140^\circ}{360^\circ} \times \pi \times 56^2)-(\frac{140^\circ}{360^\circ} \times \pi \times 10^2)$ OR $\frac{140^\circ}{360^\circ} \times \pi \times (56^2-10^2)$ (A1) $3710 \text{ cm}^2 (3709.17\ldots \text{ cm}^2)$ (A1)