Area Between a Circle and a Parabola
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What are the intersection points of the circle and the parabola ?
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What are the intersection points of the circle and the parabola ?
No score. Commit to your first instinct. We’ll show what your mind noticed and what it missed.
Correct answer
Option analysis
This option correctly finds the intersection points at and subtracts the region inside the parabola below from the lower semicircle. Correctly identify the region as the lower semicircle of radius minus the area inside the parabola bounded by .
The student computed the area for only one half of the symmetric region () instead of the full region. Remember that both curves are symmetric about the -axis, so double the area in the first quadrant or integrate from to .
The student computed half the region and incorrectly added the parabolic area instead of subtracting it from the circular sector. The condition means points lie outside or below the parabola, requiring subtraction from the semicircle rather than addition.
The student added the area under the parabola to the semicircle instead of subtracting it. Check the inequality: defines the region outside the parabola, so subtract the area between the parabola and the diameter from the semicircle.
The region is defined by (interior and boundary of a circle centered at with radius ) and (region outside/below the parabola ).
Find the total area of the bounded region satisfying both inequalities.
Find the intersection points of and . Due to symmetry about the y-axis, calculate the area in the first quadrant and multiply by 2.
Substitute into the circle equation: or . For , . Thus, the intersection points are , , and .
In the first quadrant, the region lies between and . For a given , the horizontal width goes from the parabola to the circle . Alternatively, integrating with respect to : . is the area of a quarter circle of radius , which is . . Therefore, .
The total area of the circle is . The parabola removes the upper interior portion. The computed area is , which is positive and strictly less than the semicircle area .
What are the intersection points of the circle and the parabola ?
andHow can the area of the region with be decomposed using geometry and integration?
Area of the lower semicircle of radius minus the area bounded by andWhat is the value of the integral for the area under and above the parabola between and ?
Subtracting this area from the lower semicircle of radius , what is the final area?
Quick checks
Integrating with respect to y is simpler. It takes the circle's right arc minus the parabola's right branch. This avoids breaking the integral at , where the upper boundary curve changes.