Grade 11 · Trigonometric periods
Trigonometric periods: Two cycles in the same window
Trigonometric periods: investigate two cycles in the same window with amplitude a = 1; angular frequency k = 2.
Predict what will happen, press Play, then pause and explain what changed. Every control also works without playback.
Watch the relationship
PausedHD animation studio
From experiment to screen.
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Understand what you are seeing
The idea behind the motion.
Amplitude controls vertical reach while angular frequency changes the horizontal distance needed for a full repeat. The moving point traverses a fixed interval of length 2π, so the number of displayed cycles depends on k. Fractional k can show only part of a complete period. This investigation starts with Amplitude A = 1; Angular frequency k = 2. Predict the result before playing, then change one parameter while keeping the other fixed to test the reason for the change.
A relationship to keep
f(x)=A sin(kx); period=2π/k
Read the symbols alongside the explanation. A diagram shows the relationship; the assumptions tell you when it applies.
- STEP 1
Set up the mathematical model
Predict the highest and lowest values using the amplitude alone. The starting case is “Two cycles in the same window.”
- STEP 2
Follow the changing quantity
Count cycles as the input moves from zero to 2π. Compare the count with the frequency control.
- STEP 3
Explain and test the result
Calculate 2π/k and identify matching points one period apart. The slope also depends on k, not just the amplitude.
Your turn to explain
Make a prediction. Test your reasoning.
Keep Amplitude A = 1; Angular frequency k = 2. Pause the timeline at 40%. Given input radians = 2.513, calculate wave value, period, slope. Show the substitution into the displayed formula.
Use the values specified in the question. Reset restores the initial values for this investigation.
Compare your explanation
Evaluate 1 sin((2)(2.513274))=-0.951057. A repeat requires kT=2π, giving T=2π/2=3.141593. Results: Wave value: -0.951; Period: 3.142; Slope: 0.618. Decimal values are rounded; retain the original parameters when checking.
Work through a full lesson
Connect the animation to a worked example and practice questions.