1. **State the problem:** A student stands at point A near a cliff and walks 40 m back to point B. The angle of elevation to the top of the cliff from A is 49° and from B is 32°. We need to find the height of the cliff.
2. **Set up variables and diagram:** Let $h$ be the height of the cliff and $x$ be the horizontal distance from point A to the base of the cliff.
3. **Use tangent of angles:** From point A, $$\tan(49^\circ) = \frac{h}{x} \implies h = x \tan(49^\circ)$$
From point B, which is 40 m behind A, the horizontal distance to the cliff is $x + 40$, so:
$$\tan(32^\circ) = \frac{h}{x + 40} \implies h = (x + 40) \tan(32^\circ)$$
4. **Set the two expressions for $h$ equal:**
$$x \tan(49^\circ) = (x + 40) \tan(32^\circ)$$
5. **Solve for $x$:**
$$x \tan(49^\circ) = x \tan(32^\circ) + 40 \tan(32^\circ)$$
$$x \tan(49^\circ) - x \tan(32^\circ) = 40 \tan(32^\circ)$$
$$x (\tan(49^\circ) - \tan(32^\circ)) = 40 \tan(32^\circ)$$
$$x = \frac{40 \tan(32^\circ)}{\tan(49^\circ) - \tan(32^\circ)}$$
6. **Calculate values:**
$$\tan(49^\circ) \approx 1.1504$$
$$\tan(32^\circ) \approx 0.6249$$
So,
$$x = \frac{40 \times 0.6249}{1.1504 - 0.6249} = \frac{24.996}{0.5255} \approx 47.57$$
7. **Find height $h$:**
$$h = x \tan(49^\circ) = 47.57 \times 1.1504 \approx 54.7$$
**Final answer:** The height of the cliff is approximately **54.7 metres**.
Cliff Height Da566A
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