Math Problem Statement

Solution

The image shows a graph with a shaded region, bounded by the curve y=cos(x)y = \cos(x) and the x-axis, between x=0x = 0 and x=2πx = 2\pi. The question asks to find the area of this shaded region.

Step-by-Step Solution

  1. Identify the Function and Boundaries:

    • The curve is y=cos(x)y = \cos(x).
    • The x-axis bounds the region from x=0x = 0 to x=2πx = 2\pi.
  2. Set Up the Integral:

    • The area under the curve from x=0x = 0 to x=2πx = 2\pi is given by the integral: A=02πcos(x)dxA = \int_{0}^{2\pi} \cos(x) \, dx
  3. Compute the Integral:

    • The antiderivative of cos(x)\cos(x) is sin(x)\sin(x).
    • Thus, A=[sin(x)]02πA = \left[\sin(x)\right]_{0}^{2\pi}
  4. Evaluate the Definite Integral:

    • Substitute the limits into the antiderivative: A=sin(2π)sin(0)A = \sin(2\pi) - \sin(0)
    • Since sin(2π)=0\sin(2\pi) = 0 and sin(0)=0\sin(0) = 0, we have: A=00=0A = 0 - 0 = 0
  5. Interpretation:

    • The integral itself is zero because the positive and negative areas cancel each other out. However, for the total area, we consider the absolute value of the integrand where it dips below the x-axis.
  6. Area Calculation by Splitting the Integral:

    • The area should be calculated by splitting the integral where cos(x)\cos(x) changes sign, i.e., at x=πx = \pi: A=0πcos(x)dxπ2πcos(x)dxA = \int_{0}^{\pi} \cos(x) \, dx - \int_{\pi}^{2\pi} \cos(x) \, dx
    • Each part is positive, so we take the absolute value: A=0πcos(x)dx+π2πcos(x)dxA = \left|\int_{0}^{\pi} \cos(x) \, dx \right| + \left|\int_{\pi}^{2\pi} \cos(x) \, dx \right|
    • Calculate each integral: 0πcos(x)dx=sin(x)0π=sin(π)sin(0)=00=0\int_{0}^{\pi} \cos(x) \, dx = \sin(x)\bigg|_0^\pi = \sin(\pi) - \sin(0) = 0 - 0 = 0 π2πcos(x)dx=sin(x)π2π=sin(2π)sin(π)=00=0\int_{\pi}^{2\pi} \cos(x) \, dx = \sin(x)\bigg|_{\pi}^{2\pi} = \sin(2\pi) - \sin(\pi) = 0 - 0 = 0
    • Here the results are zero, and since it's incorrect to compute like this, we should instead find the areas of each part and sum them without considering their signs.

Thus, by splitting, the total area should consider the absolute values, and for each half-period, the area is 22 because of symmetry.

Correct Final Answer: The total area is 4\boxed{4}.

Would you like to go over this explanation in more detail, or do you have any questions?


Here are five related questions:

  1. How do you find the area between a curve and the x-axis if the curve crosses the axis?
  2. What is the significance of the definite integral when computing the area under a curve?
  3. Can you explain why splitting the integral is necessary in this problem?
  4. How does symmetry help in calculating areas under trigonometric curves?
  5. What would change if the curve was y=sin(x)y = \sin(x) instead of y=cos(x)y = \cos(x)?

Tip: When calculating areas between curves and axes, remember that areas below the x-axis are considered negative unless you are specifically asked for total area.

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Math Problem Analysis

Mathematical Concepts

Calculus
Definite Integrals
Area Calculation

Formulas

Integral of cos(x)

Theorems

Fundamental Theorem of Calculus
Properties of Integrals

Suitable Grade Level

Advanced High School or College