The angle of elevation of the top of a tower from certain point A is 30°. If the observer walks 20 metres towards the tower from A, then the angle of elevation of the top of the tower increases by 15°. Find the height of the tower (in metres).
1
10(\(\sqrt3\) + 1)
2
10\(\sqrt3\)
3
\(\frac{10}{\sqrt3}\)
4
10 + \(\sqrt3\)