Answer:
9.56 yards apart.
Explanation:
Let x represent distance between both buildings.
We have been given that a clothes-line is connected from a window on one building to a window in a building across the alley. The clothes line is 10 yards long with an angle of depression of 17 degrees.
First of all, we will draw a graph to represent our given scenario.
We know that cosine relates adjacent side of right triangle to hypotenuse.
![\text{cos}=\frac{\text{Adjacent}}{\text{hypotenuse}}](https://img.qammunity.org/2020/formulas/mathematics/high-school/uz5g49rj9v0m401yk28wgbdwbqkfu7j7z3.png)
![\text{cos}(17^(\circ))=(x)/(10)](https://img.qammunity.org/2020/formulas/mathematics/high-school/djqqkt7n09auiamd72uciju46gh61htjl5.png)
![x=10\cdot \text{cos}(17^(\circ))](https://img.qammunity.org/2020/formulas/mathematics/high-school/2be4a9r0dayzzdnz163pnz41yuresw9t4n.png)
![x=10\cdot 0.956304755963](https://img.qammunity.org/2020/formulas/mathematics/high-school/madw0qhjyc95m5hr0we39jmc2l26b8dov3.png)
![x=9.56304755963](https://img.qammunity.org/2020/formulas/mathematics/high-school/e2f4oayul4nn9kpbxvhzrhxvdvhovm5nlz.png)
![x\approx 9.56](https://img.qammunity.org/2020/formulas/mathematics/high-school/v7y165ydwoq40ua4sklvd5c5xk11ozc6g9.png)
Therefore, the both buildings are 9.56 yards apart.