Calculus Volume 2 · free preview

Areas between Curves

The area of a region bounded by two curves is the integral of the top curve minus the bottom curve, or right minus left for horizontal slices, with intersections setting the limits.

1. Vertical slices

Vertical slices

2. Horizontal slices

Horizontal slices

3. Curves that cross

Curves that cross

4. Areas with geometric meaning

Areas with geometric meaning

5. Top minus bottom setup

The region between f(x) = 2 - x^2 and g(x) = x on [-2, 1] is sliced vertically. What integrand gives the strip height?

6. Finding limits from intersections

To find the area between two curves, the limits of integration are usually determined by what?

7. Horizontal slicing integrand

A region is sliced horizontally, bounded on the right by x = h(y) and on the left by x = k(y). What is the strip length?

8. Splitting at a crossing

Two curves cross at x = c inside [a, b], exchanging top and bottom positions. What must the area integral do?

9. Equal area by either slicing

The region between y = x and y = x^2 was computed as 1/6 by vertical slices and 1/6 by horizontal slices. What does the agreement demonstrate?

10. Which curve is on top

For the region between y = 2 - x^2 and y = x at the test point x = 0, which curve lies on top?

11. Area of a simple gap

The area between y = x and y = x^2 from 0 to 1 equals the integral of (x - x^2) dx. What fraction is it? Answer like 1/6.

12. Integrand sign audit

The area between y = 4 and y = x^2 on [-2, 2] has strip height 4 - x^2, always nonnegative there. At x = 0, what value does the integrand take? Answer with a number.

13. Intersection count

The curves y = 2 - x^2 and y = x intersect where x^2 + x - 2 = 0. How many intersection points enclose the finite region? Answer with a number.

14. Horizontal slice dy

When slicing horizontally, the integration variable is y and the differential is dy. As a two-letter string, what is that differential? Answer in lowercase.

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