A vertical aerial of height $9$ m stands at corner $A$ of a horizontal rectangle $ABCD$, where

Question

A vertical aerial of height $9$ m stands at corner $A$ of a horizontal rectangle $ABCD$, where $AB=12$ m and $BC=5$ m. A pupil calculates the angle of elevation $\theta$ of its top from $C$ using $\tan\theta=\dfrac9{12}$. Explain the error, write the correct trigonometric equation, and calculate the angle correct to 1 decimal place.[3]

Accepted Answer

Use $CA=13\text{ m}$: $\tan\theta=\dfrac9{13}$, so $\theta\approx34.7^\circ$.

Choosing the correct horizontal distance

Choosing the correct horizontal distance

Solution:

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