Let the area enclosed between the curves and be . If ; are integers, then the value of equals:
- A
- B
- C
- D
Let the area enclosed between the curves and be . If ; are integers, then the value of equals:
Correct answer:D
Standard Method
Given: The curves are and .
Find: The value of when , where is the enclosed area.
Using symmetry, the enclosed area is taken as four times the area in the first quadrant.
The area of the quarter circle is
Now evaluate the integral:
Therefore,
Now calculate :
Comparing with , we get and .
Hence,
Therefore, the correct option is D.
Symmetry-Based Area Setup
Given: The region is enclosed between the parabola-like curve and the circle .
Find: The required integer value .
Because the figure is symmetric about both axes, compute the area in the first quadrant and multiply by .
In the first quadrant, the circle contributes area , while the curve contributes the area under it from to .
So the enclosed area is
Then
Thus, from , the extracted integers are and , giving the required value as .
Taking only the first-quadrant area and forgetting to multiply by . This gives only one-fourth of the enclosed region. Use symmetry carefully for both the circle and the curve .
Using without noticing the modulus in . The modulus means the curve is symmetric about the -axis, so both upper and lower parts must be included.
Making a sign error while matching . From the extracted working, , so care is needed when identifying the integer term before computing .
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