(a)
Attempt to use distance formula for points D and A (M1)
\( DA = \sqrt{(35 – 24)^2 + (26 – 19)^2} = \sqrt{11^2 + 7^2} = \sqrt{121 + 49} = \sqrt{170} \approx 13.0 \) miles (A1)
Result: \( 13.0 \) (miles) (\( \sqrt{170}, 13.0384… \)) [2]

(b)
Calculate distances to find closest town (M1)
\( DB = \sqrt{(11 – 24)^2 + (24 – 19)^2} = \sqrt{(-13)^2 + 5^2} = \sqrt{169 + 25} = \sqrt{194} \approx 13.9 \) miles (A1)
\( DC = \sqrt{(28 – 24)^2 + (7 – 19)^2} = \sqrt{4^2 + (-12)^2} = \sqrt{16 + 144} = \sqrt{160} \approx 12.6 \) miles (A1)
Recognizing closest town is best estimate (town C is closest) (M1)
Temperature at C = 30°C, so estimated temperature at D = 30°C (A1)
Result: 30°C [3]