**Known values:**

Baseline distance ** AB** length, height

**of the observer at points A and B.**

*h*_{1}Vertical angles measured at A – *α*_{1}* *and** a_{2}**.

Vertical angles measured at B – *β*_{1}* *and* β***_{2}**.

**Solution:** Height of object ** Η**.

First, measure horizontal distance ** AB** and vertical angles

*α*

_{1}

*, α***and**

_{2}

*β*

_{1}

*, β***from observer points**

_{2}**and**

*A*_{1}**respectively.**

*B*_{1}Then calculate vertical distances ** C_{1}E** and

*C*_{1}O.Thus:

Also:

Thus:

Combining the previous equations: