The diagram shows a semi-circle inside a rectangle of length 120 m - OCR - GCSE Maths - Question 6 - 2017 - Paper 1

The circumference (C) of the full circle is given by:

$C = 2\pi r$

For the semi-circle, the circumference becomes:

$C_{semi-circle} = \frac{1}{2} \times C = \frac{1}{2} \times 2\pi r = \pi r$

Substituting the radius:

$C_{semi-circle} = \pi \times 60 = 60\pi \, m$

Approximate value:

$60\pi \approx 188.496 \, m$

The perimeter (P) of the shaded region includes the semicircular arc and the two straight sides of the rectangle. Therefore:

$P = C_{semi-circle} + 2 \times 60 \, m$

Substituting the known values:

$P \approx 188.496 + 120 = 308.496 \, m$

Rounding to 3 significant figures gives:

$P \approx 308 \, m$