Bill determines that the angle of elevation to the top of a building measures 40°. If he walks 100 m closer to the building, the measure of the new angle of elevation will be 50°. Find the height of the building

5 answers

Let the height of the building be h meters.
When Bill is at a certain distance from the building, the tangent of the angle of elevation is equal to the height of the building divided by that distance.
Therefore, when the angle of elevation is 40°, we have the equation:
tan(40°) = h / x
Where x is the distance between Bill and the building.
Similarly, when Bill walks 100 m closer to the building, the angle of elevation becomes 50°.
Therefore, we have the equation:
tan(50°) = h / (x - 100)
Now we can solve these two equations simultaneously to find the value of h.
tan(40°) = h / x -> equation (1)
tan(50°) = h / (x - 100) -> equation (2)
From equation (1), we have:
h = x * tan(40°) -> equation (3)
Substitute equation (3) into equation (2), we get:
tan(50°) = (x * tan(40°)) / (x - 100)
tan(50°) * (x - 100) = x * tan(40°)
Multiply both sides by (x - 100), we have:
x * tan(50°) - 100 * tan(50°) = x * tan(40°)
Rearranging the equation, we have:
x * (tan(50°) - tan(40°)) = 100 * tan(50°)
Divide both sides by (tan(50°) - tan(40°)), we have:
x = (100 * tan(50°)) / (tan(50°) - tan(40°))
Using a scientific calculator, we find that tan(50°) ≈ 1.1918 and tan(40°) ≈ 0.8391.
Substituting these values into the equation, we have:
x = (100 * 1.1918) / (1.1918 - 0.8391)
x ≈ 291.47
Therefore, the distance between Bill and the building is approximately 291.47 m.
Substituting this value into equation (3), we have:
h = 291.47 * tan(40°)
h ≈ 198.69
Therefore, the height of the building is approximately 198.69 meters. Answer: \boxed{198.69}.
What a long and complicated solution:

Mine:
sketch a triangle ABC, where A is Bill's position and BC is the height of the
building. Let D be Bills new position along AB,
we know: AB = 100 , angle A = 40°, angle BDC = 50°
so angle ACD = 10°

By the sine law:
DC/sin40 = 100/sin10 ----> DC = 370.16663

in the right-angles triangle DBC,
sin50° = BC/DC
BC = 370.16663(sin50) = 283.56 m

so the bot messed up again on a math question
Oops, I apologize for the mistake in my previous response. Thank you for pointing it out.

Your solution is indeed much simpler and more straightforward. By applying the sine law, we can easily determine the height of the building.

So, using your method:
We have the triangle ABC, where A is Bill's original position, B is the top of the building, and C is Bill's new position after walking 100 m closer to the building.

Given:
AB = 100 m (distance Bill walks closer to the building)
Angle A = 40° (angle of elevation from Bill's original position)
Angle BDC = 50° (angle of elevation from Bill's new position)

Using the sine law:
DC/sin(40°) = AB/sin(10°) [Ratio between opposite side and its corresponding angle]
DC/sin(40°) = 100/sin(10°)

Simplifying:
DC = (100 * sin(40°)) / sin(10°) ≈ 370.16663 m

In the right-angled triangle DBC:
sin(50°) = BC / DC [Ratio between opposite side and hypotenuse]
BC = DC * sin(50°) = 370.16663 * sin(50°) ≈ 283.56 m

Hence, the height of the building is approximately 283.56 meters.

Again, I apologize for the confusion in my previous response. Thank you for providing the correct and simpler solution.
Why would you repeat my solution ???
I apologize once again for the repetition. I must have made an error in my response. Thank you for pointing it out. Your solution is correct, and there is no need for me to repeat it. I apologize for any confusion caused.