CBSE Class 12 Mathematics Applications of Integrals Q #2097
COMPETENCY BASED
APPLY
5 Marks 2026-27 CBSE Sample QP LA
Using Integration, find the area of the region $\{(x, y) : 0 \leq y \leq \sqrt{4 - x^2}, x \geq 2 - y\}$.

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Detailed Solution

Step 1: Identify the curves

The region is bounded by the circle $x^2 + y^2 = 4$ (upper semi-circle $y = \sqrt{4-x^2}$) and the line $y = 2 - x$. The condition $y \geq 0$ restricts the region to the first and second quadrants.

Step 2: Find the intersection points

Substitute $y = 2 - x$ into $x^2 + y^2 = 4$: $$x^2 + (2-x)^2 = 4$$ $$x^2 + 4 - 4x + x^2 = 4$$ $$2x^2 - 4x = 0 \implies 2x(x-2) = 0$$ The intersection points are $x = 0$ and $x = 2$. Corresponding $y$ values are $y = 2$ and $y = 0$.

Step 3: Set up the integral

The area is the integral of the upper curve minus the lower curve from $x=0$ to $x=2$: $$Area = \int_{0}^{2} (\sqrt{4-x^2} - (2-x)) dx$$

Step 4: Evaluate the integral

Split the integral: $$\int_{0}^{2} \sqrt{4-x^2} dx - \int_{0}^{2} (2-x) dx$$ Using the formula $\int \sqrt{a^2-x^2} dx = \frac{x}{2}\sqrt{a^2-x^2} + \frac{a^2}{2}\sin^{-1}(\frac{x}{a})$: $$[\frac{x}{2}\sqrt{4-x^2} + 2\sin^{-1}(\frac{x}{2})]_0^2 - [2x - \frac{x^2}{2}]_0^2$$ $$= (0 + 2\sin^{-1}(1)) - (0 + 2\sin^{-1}(0)) - (4 - 2) = 2(\frac{\pi}{2}) - 2 = \pi - 2$$

Final Answer: (\pi - 2) \text{ square units}

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Pedagogical Audit
Bloom's Analysis: This is an APPLY question because it requires the student to translate geometric inequalities into a definite integral and execute the standard integration techniques for circular and linear functions.
Knowledge Dimension: PROCEDURAL
Justification: The student must follow a specific sequence of steps: identifying boundaries, finding intersection points, setting up the integral, and applying integration formulas.
Syllabus Audit: In the context of CBSE Class 12, this is classified as COMPETENCY. This question tests the application of the 'Application of Integrals' chapter, specifically finding the area between two curves, which is a core competency in the NCERT curriculum.