Answer:
630 .18 feet tall is the gateway arch .
Explanation:
As given
The angle of elevation from a park bench 778 feet from the base of the Gateway Arch in St. Louis, Missouri is 39 degrees.
Now by using the trignometric property
![tan\theta = (Perpendicular)/(Base)](https://img.qammunity.org/2020/formulas/mathematics/high-school/ql007qnp16yb1h9w49ei9vzkh1kcb5cvd3.png)
As diagram is given below .
![\theta = 39^(\circ)](https://img.qammunity.org/2020/formulas/mathematics/high-school/nwrhwwv9aumzq0wge3xtswcfj0gq00z316.png)
![tan39^(\circ)= (AB)/(CB)](https://img.qammunity.org/2020/formulas/mathematics/high-school/7z8t4q9tdgzt9azew6xjzzu9kv2hz8pzlm.png)
CB = 778 feet
![tan 39^(\circ) = 0.81 (Approx)](https://img.qammunity.org/2020/formulas/mathematics/high-school/qdqw0g3jo2sxkih7isk9qbdz26trpwx71v.png)
![0.81= (AB)/(778)](https://img.qammunity.org/2020/formulas/mathematics/high-school/h4v7swa7ca3yupxcvzgnyeep4qe24xrwq1.png)
AB = 0.81 × 778
AB = 630 .18 feet
Therefore the 630 .18 feet tall is the gateway arch .