Math Problem Statement

A pole that is 3.1 m tall casts a shadow that is 1.39 m long. At the same time, a nearby building casts a shadow that is 36.25 m long. How tall is the building? Round your answer to the nearest meter.

Solution

To determine the height of the building using the concept of similar triangles, we can follow these steps:

Given:

  • Height of the pole hp=3.1h_p = 3.1 meters
  • Length of the pole's shadow sp=1.39s_p = 1.39 meters
  • Length of the building's shadow sb=36.25s_b = 36.25 meters

Let hbh_b be the height of the building.

The ratio of the height of the pole to the length of its shadow is equal to the ratio of the height of the building to the length of its shadow. This gives us the proportion:

hpsp=hbsb\frac{h_p}{s_p} = \frac{h_b}{s_b}

Substituting the given values:

3.11.39=hb36.25\frac{3.1}{1.39} = \frac{h_b}{36.25}

Solving for hbh_b:

hb=3.1×36.251.39h_b = \frac{3.1 \times 36.25}{1.39}

First, calculate 3.1×36.253.1 \times 36.25:

3.1×36.25=112.3753.1 \times 36.25 = 112.375

Next, divide by 1.39:

hb=112.3751.3980.86h_b = \frac{112.375}{1.39} \approx 80.86

Rounding to the nearest meter:

hb81 metersh_b \approx 81 \text{ meters}

Thus, the height of the building is approximately 81 meters.

Would you like more details on the calculation or have any questions?

Here are some related questions you might find interesting:

  1. How do similar triangles help in real-world applications like construction?
  2. What are other methods to measure the height of tall structures?
  3. How does the time of day affect the length of shadows?
  4. Can this method be used for objects that are not vertical?
  5. What is the role of the sun's angle in shadow length measurement?
  6. How can we ensure the accuracy of measurements taken in this way?
  7. What are some practical uses of trigonometry in everyday life?
  8. How can technology aid in measuring heights and distances accurately?

Tip: When using shadows to measure heights, ensure that the surface is flat and the objects are vertical to minimize errors.

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Math Problem Analysis

Mathematical Concepts

Geometry
Proportion

Formulas

-

Theorems

Similar Triangles

Suitable Grade Level

Grades 7-9