Pearson Algebra 2 Common Core, 2011
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Pearson Algebra 2 Common Core, 2011 View details
3. Right Triangles and Trigonometric Ratios
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Exercise 35 Page 925

Use the trigonometric ratio for tangent. Then, subtract the heights.

33.4 feet

Practice makes perfect

We are 330 feet from the base of a building. The angles of elevation to the top and bottom of a flagpole on top of the building are 55^(∘) and 53^(∘). We want to find the height x of the flapole. To do so, we will start by drawing a diagram of this situation.

Now, we will calculate the height h from the bottom of the building to the bottom the flagpole. From the diagram, we can see that the ground and the building form a right angle. Then, we can use the trigonometric ratio for tangent to find the height h. tan θ = Opposite/AdjacentIn this case, the measure of the angle is 53^(∘), the length of the adjacent side is 330, and the length of the opposite side is h. tan θ = Opposite/Adjacent ⇒ tan 53^(∘) = h/330 Let's solve this equation to obtain the value of h.

tan 53^(∘) = h/330
330 tan 53^(∘) = h
437.924791 ... = h
437.9 ≈ h
h ≈ 437.9

Next, we want to find the height H from the bottom of the building to the top of the flagpole. We will use again the trigonometric ratio for tangent. This time the measure of the angle is 55^(∘), the length of the adjacent side is 330, and the length of the opposite side is H. tan 55^(∘) = H/330 We will solve this equation to obtain the value of H.

tan 55^(∘) = H/330
330 tan 55^(∘) = H
471.288884 ... = H
471.3 ≈ H
H ≈ 471.3

Now that we have the heights, we will subtract them to determine the height of the flagpole. x= H - h ⇒ x=33.4 feet