Math Problem Statement

An irrigation system uses a straight sprinkler pipe r = 400 ft long that pivots around a central point as shown. Because of an obstacle the pipe is allowed to pivot through 𝜃 = 220° only. Find the area irrigated by this system. (Round your answer to the nearest whole number.)

Solution

To find the area irrigated by the sprinkler system, we can treat the area as a sector of a circle. The area AA of a sector of a circle is given by:

A=θ360×πr2A = \frac{\theta}{360^\circ} \times \pi r^2

where:

  • θ\theta is the central angle in degrees.
  • rr is the radius of the circle (the length of the sprinkler pipe).

Given:

  • r=400r = 400 ft
  • θ=220\theta = 220^\circ

Substituting these values into the formula:

A=220360×π×(400)2A = \frac{220^\circ}{360^\circ} \times \pi \times (400)^2

A=220360×π×160000A = \frac{220}{360} \times \pi \times 160000

A=1118×π×160000A = \frac{11}{18} \times \pi \times 160000

A0.6111×502654.82 square feetA \approx 0.6111 \times 502654.82 \text{ square feet}

A307,876 square feetA \approx 307,876 \text{ square feet}

So, the area irrigated by the system is approximately 307,876 square feet.

Would you like more details or have any questions?

Here are 5 related questions:

  1. How would the area change if the sprinkler pipe length was doubled?
  2. What would be the area if the angle was reduced to 180°?
  3. How does changing the angle θ affect the area irrigated?
  4. If the radius was shortened to 200 ft, what would the new area be?
  5. How is the formula for the area of a sector derived?

Tip: Always ensure the angle is in degrees when using this formula for a sector of a circle.

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Math Problem Analysis

Mathematical Concepts

Geometry
Circle Sector

Formulas

Area of a sector of a circle

Theorems

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Suitable Grade Level

High School