Calculate CD, the height of the observation deck above the ground.

Calculate the angle of depression from A to B.

$\tan 48^\circ  = \frac{{{\text{CD}}}}{{250}}$    (M1)

Note:     Award (M1) for correct substitution into the tangent ratio.

$({\text{CD}} = ){\text{ }}278{\text{ }}({\text{m}}){\text{ }}(277.653 \ldots )$    (A1)     (C2)

[2 marks]

$\tan {\text{ABC (or equivalent)}} = \frac{{\frac{4}{3} \times 277.653 \ldots }}{{250}}$     (M1)(M1)(M1)

Note:     Award (M1) for $\frac{4}{3}$ multiplying their part (a), (M1) for substitution into the tangent ratio, (M1) for correct substitution.

OR

$90 - {\tan ^{ - 1}}\left( {\frac{{250}}{{\frac{4}{3} \times 277.653 \ldots }}} \right)$    (M1)(M1)(M1)

Note:     Award (M1) for $\frac{4}{3}$ multiplying their part (a), (M1) for substitution into the tangent ratio, (M1) for subtracting from 90 and for correct substitution.

${\text{(angle of depression}} = {\text{) }}56.0^\circ {\text{ }}(55.9687 \ldots )$    (A1)(ft)     (C4)

Note:     Follow through from part (a).

[4 marks]