(a) Describe briefly the Gunters' chain. (b) A farmer surveyed his triangular farmland with a base length of 2 km and a perpendicular length of 1200m. Calcu...

Answer Details

(a) The Gunter's chain

The Gunter's chain is a land-measuring (surveying) chain that is 66 feet (about 20.1 m) long and made up of 100 links, each link being 7.92 inches. It is used to measure horizontal distances on farmland during chain surveying. Ten square chains make one acre, which makes it convenient for computing land area.

(b) Area of the triangular farm

The measurements must be in the same unit. Perpendicular length = 1200 m = 1.2 km, base = 2 km.

\[ \text{Area} = \tfrac{1}{2} \times \text{base} \times \text{perpendicular height} \]

\[ \text{Area} = \tfrac{1}{2} \times 2\,\text{km} \times 1.2\,\text{km} = 1.2\,\text{km}^2 \]

(Equivalently \(\tfrac{1}{2} \times 2000\,\text{m} \times 1200\,\text{m} = 1{,}200{,}000\,\text{m}^2 = 120\ \text{hectares}\).)

(c) Four precautions to eliminate errors when chaining

• Keep the chain straight, taut and horizontal during measurement.
• Use ranging poles to keep the line straight between the two points.
• Count the arrows/pins carefully and record readings correctly to avoid miscounting a chain length.
• Check the chain for stretched, bent or missing links before use and correct for sag and slope.

(d) Four factors in choosing a site for a new school garden

• Fertile, well drained soil.
• Nearness to a reliable source of water.
• Nearness to the school and accessibility.
• A fairly level, gentle land free from erosion, with adequate sunlight.