An object is observed from the points A, B and C lying in a horizontal straight line which passes directly underneath the object. The angular elevation at A is \( \theta \), at B is \( 2\theta \), and at C is \( 3\theta \). If AB = a, BC = b, and the height of the object is h, then the height of the object is
Show Hint
When dealing with objects at different points, use trigonometric functions to relate the angles and distances to calculate the height.
Step 1: Use trigonometry.
Use the tangent function for the angular elevations at points A, B, and C to create equations involving the height of the object.
Step 2: Conclusion.
After solving the trigonometric equations, we find that the height of the object is \( \frac{a}{2} \left( b - a \right) \).
Final Answer:
\[
\boxed{\frac{a}{2} \left( b - a \right)}
\]