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With x measured in radians, what is the least positive period?

Read the idea, work independently, then explain what changed.

TOPIC 01

Trigonometric ratios and function graphs

In a width of 2π along the x-axis this curve completes two cycles. Its amplitude is 3, independently of its period.

PREDICT → MOVE → EXPLAIN

See amplitude, period and phase together.

Predict the number of cycles and the horizontal shift. Switch angle units without changing the curve.

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Try it. Leave your reasoning visible.

Use one hint at a time. A correction explains what changed, not just the final answer.

01 / Standard#Your turn

With x measured in radians, what is the least positive period?

y=3sin⁡(2x)y=3\sin(2x)
  1. First value2π2\pi
  2. Second value3π3\pi
  3. Third valueπ\pi
  4. Fourth valueπ2\tfrac\pi2

Working and explanation

BUILD THE REASONING

Hint 1
The factor 3 affects vertical distances, not the period.
Hint 2
Find the smallest positive T for which the angle 2x advances by 2π.
Worked solution
  1. Set the change in the argument to one full turn.

    2(x+T)−2x=2π2(x+T)-2x=2\pi
  2. Solve for the period in x.

    2T=2π⇒T=π2T=2\pi\Rightarrow T=\pi

C: the least positive period is π radians.

Checks and common pitfalls: In a width of 2π along the x-axis this curve completes two cycles. Its amplitude is 3, independently of its period.

Think first. Reveal a hint when the class is ready.

Focus on one question

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Curriculum and source notes ↗