Area under a curve
Age 18 · Maths
For a positive function, the integral between two bounds is the area caught between its graph and the horizontal axis. Picture it as a shaded region whose top edge is the curve and whose sides are two vertical lines.
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In the picture
- The curve: the graph of the positive function whose height shapes the region.
- The shaded region: the area under the curve between the two bounds.
- The left vertical line: the lower bound of the interval.
- The right vertical line: the upper bound of the interval.
Examples
- Distance travelled from a speed-time graph when speed changes.
- Water collected from a rainfall rate that changes during the day.
Key takeaways
- If the curve stays above the horizontal axis, the integral gives a positive area.
- Changing either bound changes the width and size of the shaded area.
Quiz: Area under a curve (Age 18)
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For a positive function, what does the integral between two bounds represent?
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If the curve stays above the horizontal axis, what sign does the integral have?
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What happens to the shaded area if either bound is changed?
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