Explanation:

Let's break it down stepwise:

- Let's say building height = h, tree height = 50 m.

- Let both stand on the same level, separation between tree and building = d metres.

- From the top of the tree, angle of elevation to the top of the building = 30°

? tan 30° = (h - 50)/d ? 1/v3 = (h - 50)/d ? d = v3(h - 50)

- From the bottom of the tree, angle of elevation to top of building = 60°

? tan 60° = h/d ? v3 = h/d ? d = h/v3

- Set d = v3(h - 50) = h/v3

? Cross-multiplied: v3(h - 50) = h/v3

? 3(h - 50) = h

? 3h - 150 = h

? 2h = 150

? h = 75

Options:

- Option 1: 50v3 — Incorrect

- Option 2: 75 — Correct!

- Option 3: 50(v3 + 1) — Incorrect

- Option 4: 75v3 — Incorrect