Math Problem Statement

Evaluate the definite integral \( \int_0^{35} g(x) \, dx \) using the provided graph of \( g(x) \), which consists of two straight lines and a semicircle.

Solution

The problem involves evaluating definite integrals of a piecewise-defined function g(x)g(x), represented by a graph. Here's the breakdown of the situation and the steps to calculate the remaining part (c):

Observations

  1. The graph is composed of:
    • Two straight lines between x=0x = 0 to x=10x = 10 and x=10x = 10 to x=20x = 20.
    • A semicircle from x=20x = 20 to x=35x = 35.

Given:

  • 010g(x)dx=100\int_0^{10} g(x) \, dx = 100
  • 1030g(x)dx=50π\int_{10}^{30} g(x) \, dx = -50\pi

For part (c), 035g(x)dx\int_0^{35} g(x) \, dx, the total integral can be broken down as: 035g(x)dx=010g(x)dx+1030g(x)dx+3035g(x)dx\int_0^{35} g(x) \, dx = \int_0^{10} g(x) \, dx + \int_{10}^{30} g(x) \, dx + \int_{30}^{35} g(x) \, dx

Steps:

  1. Use the first segment:
    010g(x)dx=100\int_0^{10} g(x) \, dx = 100 (already given).

  2. Semicircle calculation (middle segment):
    1030g(x)dx=50π\int_{10}^{30} g(x) \, dx = -50\pi (already given).

  3. Calculate the last segment (x=30x = 30 to x=35x = 35): The function appears to return to 0 along a straight line. The area under the curve for this part is triangular:

    • Height = 10 (from y=0y = 0 to y=10y = 10)
    • Base = 5 (from x=30x = 30 to x=35x = 35) Area = 12×base×height=12×5×10=25\frac{1}{2} \times \text{base} \times \text{height} = \frac{1}{2} \times 5 \times 10 = 25.
  4. Add all components:
    035g(x)dx=100+(50π)+25\int_0^{35} g(x) \, dx = 100 + (-50\pi) + 25

Final Answer:

035g(x)dx=12550π\int_0^{35} g(x) \, dx = 125 - 50\pi

Would you like detailed explanations of specific parts or have additional questions?

Related Questions:

  1. How do you compute definite integrals for piecewise functions?
  2. Why does the semicircle contribute a negative value to the integral?
  3. What is the geometric interpretation of definite integrals in real-world contexts?
  4. How can areas of basic shapes (triangles, circles) help in definite integration?
  5. What happens if the function crosses the x-axis multiple times?

Tip:

Always separate a complex graph into manageable geometric or functional components before integrating.

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Math Problem Analysis

Mathematical Concepts

Definite Integration
Piecewise Functions
Geometry of Areas

Formulas

Area of a triangle: \( \frac{1}{2} \times \text{base} \times \text{height} \)
Area of a semicircle: \( \frac{1}{2} \pi r^2 \)

Theorems

Fundamental Theorem of Calculus
Geometric Interpretation of Integrals

Suitable Grade Level

Grades 11-12 or introductory college calculus