Mathematics Grade 12 15 min

Graph sine and cosine functions

Graph sine and cosine functions

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1

Introduction & Learning Objectives

Learning Objectives Identify the amplitude, period, phase shift, and vertical shift from a sinusoidal equation. Graph transformations of sine and cosine functions of the form y = A sin(B(x - C)) + D and y = A cos(B(x - C)) + D. Determine the equation of a sinusoidal function given its graph. Analyze the effect of changing parameters A, B, C, and D on the graph of a sinusoidal function. Connect the unit circle definition of sine and cosine to their graphical representations over the domain of all real numbers. Model and interpret real-world periodic phenomena using sine and cosine functions. Ever wonder how we can mathematically model the rhythmic patterns of ocean tides, sound waves, or even the alternating current in our homes? 🌊 This tutorial delves into the graphical re...
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Key Concepts & Vocabulary

TermDefinitionExample Sinusoidal FunctionA function that describes a smooth, repetitive oscillation or wave. It can be expressed as either a sine or cosine function with transformations.y = 3 sin(2(x - π)) + 5 is a sinusoidal function. AmplitudeThe absolute value of half the vertical distance between the maximum and minimum values of the function. It represents the wave's 'height' from its central axis.In y = -4 cos(x), the amplitude is |-4| = 4. The function oscillates between a maximum of 4 and a minimum of -4. PeriodThe length of the smallest horizontal interval over which the function's graph completes one full cycle.The basic function y = sin(x) has a period of 2π. The function y = sin(2x) completes a full cycle in half the horizontal distance, so its period is π....
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Core Formulas

General Form of Sinusoidal Functions y = A \sin(B(x - C)) + D \quad \text{and} \quad y = A \cos(B(x - C)) + D This is the standard form used to identify all transformations. 'A' controls amplitude and reflection, 'B' affects the period, 'C' is the phase shift, and 'D' is the vertical shift (midline). Period Formula \text{Period} = \frac{2\pi}{|B|} Use this formula to calculate the length of one full cycle of the function. Remember that B is the coefficient of x *after* factoring it out from the phase shift term. Key Graphing Points A cycle is defined by 5 key points: a start, a quarter-way point, a midpoint, a three-quarters point, and an end. For a transformed function, the cycle starts at x = C and ends at x = C + Period. The...

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Sample Practice Questions

Challenging
The height of a Ferris wheel car above the ground is modeled by h(t) = 25 sin(Ï€/10 * (t - 5)) + 30, where t is in seconds. What is the maximum height the car reaches?
A.25 feet
B.55 feet
C.30 feet
D.5 feet
Challenging
A sinusoidal function has a maximum at (Ï€/4, 2) and a subsequent minimum at (3Ï€/4, -4). Which two equations could represent this function?
A.y = 3sin(2(x - π/4)) - 1 and y = 3cos(2x) - 1
B.y = 3sin(2x) - 1 and y = 3cos(2(x - π/4)) - 1
C.y = 3sin(x) - 1 and y = 3cos(x - π/4) - 1
D.y = 3sin(Ï€x) - 1 and y = 3cos(Ï€(x - 1/4)) - 1
Challenging
The function f(x) = A sin(B(x - C)) + D passes through the points (0, 3), (Ï€/2, 5), and (Ï€, 3). Assuming A > 0 and the period is 2Ï€, what is the equation?
A.y = 2 sin(x - π/2) + 3
B.y = 5 sin(x) + 3
C.y = 2 sin(x) + 3
D.y = 2 sin(x + π/2) + 3

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