CBSE Class 12 Mathematics Notes Chapter 8 Application of Integrals

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The application of integrals is used to calculate the area and volume of different 2-D and 3-D curves, and they have various applications in mathematics. 

  • They help us calculate the area of an arc of a circle, irregular boundaries, the volume of various curves, and the area between the two curves. 
  • Integrals include the summation of discrete data, and their applications cover basic integral concepts such as the fundamental theorem of calculus. 
  • It is used in the fields of architecture, electrical engineering, medical science and statistics.
  • In mathematics, integrals are used to calculate the area under a curve and the area of a region bounded by a curve and a line.

Application of integrals is important for class 12 students, as well as engineering mathematics. CBSE Class 12 Mathematics Notes for Chapter 8 Application of Integrals are given in the article below for easy preparation and understanding of the concepts involved.

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Application of Integrals

There are various applications of integrals. Some of them are as follows:

  • It is used to calculate the area under simple curves.
  • The concept is used to find areas enclosed by lines, arcs of circles, parabolas, and ellipses.
  • Integrals are used to find out the area between two curves.
  • It is used to find out the centroids of areas of the triangle with curved boundaries.
  • In the field of statistics, it is used to determine survey data to improve marketing plans for different companies.

Area Between the Curve and the Axis

  • The area of the region bounded by the curve y = f(x), x-axis, and the lines x = a and x = b (b > a) is given by the formula

Area = ∫ab y dx = ∫ab f(x) dx

The area between the curve and the axis

The area between the curve and the axis

  • The area of the region bounded by the curve x = Φ(y), y-axis, and the lines y = c and y = d (b > a) is given by the formula

Area = ∫cd x dy = ∫cd Φ(y) dy


Area Between Two Curve

  • The area of the region enclosed between two curves y = f(x), y = g(x), and the lines x = a, x = b is given by the formula

Area = ∫ab [f(x) - g(x)] dx

Where f(x) ≥ g (x) in [a, b]

Area Between Two Curve

Area Between Two Curve

  • If f(x) ≥ g (x) in [a, c] and f(x) ≤ g (x) in [c, b], a < c < b, then

Area = ∫ac [f(x) - g(x)] dx + ∫cb [g(x) - f(x)] dx


Method to Find Area Under Curve

  • To calculate area, first, find the equation of the curve, y = f(x), as well as its limits and axis.
  • The integration i.e. antiderivative of the curve is found.
  • The upper and lower limits are applied to the integral result, and the difference provides the area under the curve.

Area in Polar Coordinates

  • Consider the region OKM bounded by a polar curve r = f(θ) and two semi-straight lines θ = ⍺ and θ = ꞵ.
  • The area of the polar region is given by

Area = 1/2 ∫⍺ꞵ r2 dθ = 1/2 ∫⍺ꞵ f2(θ) dθ

Area in Polar Coordinates

Area in Polar Coordinates


Area Between Two Polar Curves

  • The area of a region between two polar curves r = f(θ) and r = g(θ) in the sector [⍺, ꞵ] is expressed by the integral

Area = 1/2 ∫⍺ꞵ [f2(θ) – g2(θ)] dθ

Area Between Two Polar Curves

Area Between Two Polar Curves


Some Standard Curves and their Equation

  • Straight Line:

x = a and x = – a, where a > 0

Straight Line

Straight Line

  • Circle:

x2 + y2 = a2

Circle

Circle

  • Parabola:

y2 = 4ax or y2 = – 4ax

Parabola

Parabola

  • Ellipse

x2/a2 + y2/b2 = 1

Ellipse

Ellipse

There are Some important List Of Top Mathematics Questions On Applications Of Integrals Asked In CBSE CLASS XII

CBSE CLASS XII Related Questions

  • 1.
    Assertion (A) : In an experiment of throwing an unbiased die, the probability of getting a prime number given that number appearing on the die being odd is \( \frac{2}{3} \).
    Reason (R) : For any two events \( A \) and \( B \), \( P(A|B) = \frac{P(A \cup B)}{P(B)} \).

      • Both Assertion (A) and Reason (R) are true and the Reason (R) is the correct explanation of the Assertion (A).
      • Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
      • Assertion (A) is true and Reason (R) is false.
      • Assertion (A) is false and Reason (R) is true.

    • 2.

      For two vectors \(\vec{a}\) and \(\vec{b}\):  

      Assertion (A): \[ |\vec{a}\times\vec{b}|^2+(\vec{a}\cdot\vec{b})^2 = |\vec{a}|^2|\vec{b}|^2 \] Reason (R): \[ |\vec{a}\times\vec{b}| = (\vec{a}\cdot\vec{b})\tan\theta, \quad \theta\neq\frac{\pi}{2}. \]

        • Both Assertion (A) and Reason (R) are true and the Reason (R) is the correct explanation of the Assertion (A).
        • Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
        • Assertion (A) is true, but Reason (R) is false.
        • Assertion (A) is false, but Reason (R) is true.

      • 3.
        For a square matrix \(A\), \[ (3A)^{-1}= \]

          • \( 3A^{-1} \)
          • \( 9A^{-1} \)
          • \( \frac{1}{3} A^{-1} \)
          • \( \frac{1}{9} A^{-1} \)

        • 4.

          Find the domain of \[ q(x)=\cos^{-1}(4x^2-3). \] Hence, find the value of \(x\) for which \[ q(x)=0. \] Also, write the range of \[ 3q(x)-\pi. \] 


            • 5.
              If \[ \frac{d}{dx}(F(x))=\frac{1}{e^x+1}, \] then find \(F(x)\), given that \[ F(0)=\log\left(\frac{1}{2}\right). \]


                • 6.
                  The least value of \[ f(x)=e^{-x} \] in the interval \[ [0,3] \] is:

                    • \( e^{-3} \)
                    • \( -1 \)
                    • \( 1 \)
                    • \( -e^3 \)
                  CBSE CLASS XII Previous Year Papers

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