Mathematics
Grade 12
15 min
Graph sine functions
Graph sine functions
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1
Introduction & Learning Objectives
Learning Objectives
Identify the amplitude, period, phase shift, and vertical shift from the equation of a sine function.
Graph the parent function y = sin(x) and identify its key features.
Graph transformations of the sine function in the form y = A sin(B(x - C)) + D.
Determine the equation of a sinusoidal function given its graph.
Analyze the effect of each parameter (A, B, C, D) on the graph of y = sin(x).
Determine the domain and range of any transformed sine function.
Apply the five-point plotting method to accurately sketch one cycle of a sine function.
Ever wondered how sound waves are visualized or how we model daily temperature cycles? 🌊 It all starts with the elegant, repeating curve of the sine function.
This tutorial will guide you through the process of grap...
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Key Concepts & Vocabulary
TermDefinitionExample
AmplitudeHalf the vertical distance between the maximum and minimum values of the function. It represents the 'height' of the wave from its central axis and is given by |A|.For the function y = 4 sin(x), the amplitude is 4. The graph oscillates between y = -4 and y = 4.
PeriodThe length of one complete horizontal cycle of the graph. It is the distance over which the function's shape repeats.For y = sin(2x), the period is 2π/2 = π. The graph completes one full wave over an interval of π radians.
Phase ShiftThe horizontal translation of the sinusoidal graph. In the form y = A sin(B(x - C)) + D, the phase shift is C. A positive C shifts the graph to the right, and a negative C shifts it to the left.For y = sin(x - π/3), the phase shift is π/3. The graph i...
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Core Formulas
Standard Form of a Sine Function
y = A \sin(B(x - C)) + D
This is the general form used to graph transformations. 'A' controls the amplitude and reflection over the x-axis. 'B' controls the period. 'C' controls the phase (horizontal) shift. 'D' controls the vertical shift and midline.
Period Formula
\text{Period} = \frac{2\pi}{|B|}
Use this formula to calculate the length of one full cycle of the sine wave. The standard period of y = sin(x) is 2Ï€ because B=1.
Key Points for One Cycle
Start: x = C \newline Quarter-point: x = C + \frac{\text{Period}}{4} \newline Mid-point: x = C + \frac{\text{Period}}{2} \newline Three-quarter-point: x = C + \frac{3 \cdot \text{Period}}{4} \newline End: x = C + \text{Period}
These five x-values c...
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Challenging
A sinusoidal graph has a maximum at (Ï€/3, 4) and an adjacent minimum at (2Ï€/3, 0). Which of the following is a possible equation for the graph?
A.y = 2 cos(3(x - π/6)) + 2
B.y = 2 sin(3(x - π/6)) + 2
C.y = 4 sin(3(x - π/3)) + 2
D.y = 2 sin(1.5(x - π/3)) + 2
Challenging
The graph of the function y = A sin(x), where A > 0, passes through the point (Ï€/6, 2). What is the value of A?
A.1
B.2
C.4
D.√2
Challenging
The height h in meters of a tide is modeled by h(t) = 3 sin( (Ï€/6)(t - 3) ), where t is the number of hours after midnight. What is the time of the first high tide after midnight?
A.t = 3 hours (3:00 AM)
B.t = 4.5 hours (4:30 AM)
C.t = 9 hours (9:00 AM)
D.t = 6 hours (6:00 AM)
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