A student says "sin(x) = 0.5 has two solutions." In what context is this true? In what context could it have infinitely many solutions? Explain clearly.
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Question 13 [4 marks]
Write a guide explaining how the parameters a, k, d, c in y = a·sin(k(x-d))+c each affect the graph. Include a transformation table.
The depth of water in a harbour is modeled by d(t) = 4sin(πt/6) + 8, where d is in metres and t is hours after midnight. a) What is the maximum depth and when does it first occur? b) A boat needs 5m clearance. During what hours can it safely enter?
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Question 15 [4 marks]
The temperature in a city varies sinusoidally over a year. The max temperature is 28°C in July (month 7) and the min is -8°C in January (month 1). a) Write a cosine model T(m). b) During which months is temperature above 20°C?
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Question 16 [3 marks]
A pendulum swings according to θ(t) = 0.2cos(4πt), where θ is the angle in radians and t is in seconds. a) What is the period of one swing? b) How many complete swings in 10 seconds?
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Question 17 [4 marks]
Two musicians play notes modeled by y₁ = sin(440·2πt) and y₂ = sin(442·2πt). The "beat" they hear has frequency |440-442|/2 = 1 Hz. Explain what happens when you add these two waves (use the sum-to-product identity if possible).
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Evaluation Rubric
Level
Description
%
4
Thorough, insightful, high degree of effectiveness