**Known values:**

Baseline distance ** AB** length, height

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

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

**.**

*δ*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*

_{2}**and**

*, δ*

*β*

_{1}

*, β***from observer points**

_{2}**and**

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

*B*_{1}In triangle A_{1}ΕB_{1},

Same for triangle A_{1}OB_{1},

Then calculate sloping distance *A _{1}*

**:**

*Ε*and

Same for sloping distance ** A_{1}O**:

and

Then:

Thus: