```

H (to be found)

|\

| \

| \

| \

| \

| \

| \

|72° \

L | \

o-------- o B (building)

|39°

|

|

|

|

|

|

|

|

|

|

|

|

|

```

We have a right triangle formed by the observer on the ladder (point L), the base of the building (point B), and a point directly beneath the observer (point O). We can use the tangent function to find the height of the building:

```

tan(72°) = H / LO (1)

tan(39°) = H / OB (2)

```

We want to solve for H, so let's rearrange equation (1) to isolate H:

```

tan(72°) = H / LO

H = LO * tan(72°)

```

Now we can substitute this expression for H into equation (2) and solve for OB:

```

tan(39°) = H / OB

tan(39°) = LO * tan(72°) / OB

OB = LO * tan(72°) / tan(39°)

```

We know that LO is 29 feet, so we can plug in the numbers and solve:

```

OB = 29 * tan(72°) / tan(39°)

OB ≈ 48.7 feet

```

Finally, we can use the Pythagorean theorem to find H:

```

H^2 = OB^2 + BO^2

H^2 = OB^2 + (LO)^2

H^2 = (48.7)^2 + (29)^2

H^2 ≈ 2881.69

H ≈ 53.64 feet

```

Therefore, the height of the building is approximately 53.64 feet.