Step-by-Step Process

Part of Area Under Curves · Section 5 of 11

Deep DiveUnit: GraphsGCSE

This deep dive covers Step-by-Step Process within Area Under Curves for GCSE Mathematics. Revise Area Under Curves in Graphs for GCSE Mathematics with 9 exam-style questions and 10 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 5 of 11 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.

Step-by-Step Process

  1. Identify the strip width h and the number of strips n
  2. List the x-values at each strip boundary: x₀, x₁, x₂, ..., xₙ
  3. Calculate (or read from the graph) the y-value at each x-value
  4. Identify: first y-value = y₀, last y-value = yₙ, middle values = y₁ to yₙ₋₁
  5. Apply the formula: Area ≈ h/2 × (y₀ + yₙ + 2(y₁ + y₂ + ... + yₙ₋₁))
  6. Include units in your answer (e.g. m, km, litres)

Alternative approach: calculate each individual trapezium using Area = ½(a + b)h, then add them all up. This gives the same answer.

Practice questions for Area Under Curves

On a velocity-time graph, what does the area under the curve represent?

  • A. The acceleration
  • B. The average velocity
  • C. The distance (or displacement) travelled
  • D. The speed at a given moment
1 markfoundation

Explain whether the trapezium rule gives an overestimate or underestimate for the area under the curve y = x² between x = 0 and x = 3. Justify your answer.

2 markshigher

Quick recall flashcards

What is the trapezium rule used for?
Estimating the area under a curve by dividing it into trapezium-shaped strips. Each strip is a trapezium (not a rectangle or triangle). The more strips used, the more accurate the estimate. It is an approximation — the actual area is slightly different because the tops of the strips are straight lines, not curves.
What does the area under a speed-time graph represent?
Distance travelled. Area under a speed-time graph = distance travelled This works for any speed-time or velocity-time graph. Even if the graph is curved, the area still represents distance. Units: if speed is m/s and time is s, then area has units of metres (m).

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