Given the functions defined by
$f(x) = ext{cos}(x - 45^ ext{o})$
and
$g(x) = -2 ext{sin}x$, where $x ext{ } ext{is in } [0^ ext{o}; 360^ ext{o}]$
5.1 Draw sketch graphs of $f$ and $g$ on the same set of axes provided in the ANSWER BOOK - NSC Technical Mathematics - Question 5 - 2024 - Paper 2
Question 5
Given the functions defined by
$f(x) = ext{cos}(x - 45^ ext{o})$
and
$g(x) = -2 ext{sin}x$, where $x ext{ } ext{is in } [0^ ext{o}; 360^ ext{o}]$
5.1 Dra... show full transcript
Worked Solution & Example Answer:Given the functions defined by
$f(x) = ext{cos}(x - 45^ ext{o})$
and
$g(x) = -2 ext{sin}x$, where $x ext{ } ext{is in } [0^ ext{o}; 360^ ext{o}]$
5.1 Draw sketch graphs of $f$ and $g$ on the same set of axes provided in the ANSWER BOOK - NSC Technical Mathematics - Question 5 - 2024 - Paper 2
Step 1
5.1 Draw sketch graphs of f and g on the same set of axes.
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Answer
To sketch the graphs of the functions:
Graph of f(x):
The function f(x)=extcos(x−45exto) is a cosine wave shifted to the right by 45exto. Its amplitude is 1 and it oscillates between -1 and 1.
The x-intercepts can be found where f(x)=0:
x−45exto=90exto+kimes360extox=135exto+kimes360exto (for k=0)
x=135exto
The turning points occur at x=45exto,225exto.
Graph of g(x):
The function g(x)=−2extsinx has an amplitude of 2. This function is also periodic and oscillates between -2 and 0.
The minimum value occurs when g(x) takes the value of -2 which occurs at x=270exto.
Graphing: Plot both graphs on the same set of axes, with turning points, intercepts, and the y-intercept (for f: (0,extcos(−45exto))).
Step 2
5.2 Write down the value of x for which g is a minimum.
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Answer
The minimum value of g(x)=−2extsinx occurs at:
x=270exto
Step 3
5.3 Write down the period of g.
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Answer
The period of g(x)=−2extsinx is:
360exto
Step 4
5.4 Use the letters A and B to indicate on the graphs where -1/2 cos(x - 45°) = sin x.
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Answer
To find the points where -rac{1}{2} ext{cos}(x - 45^ ext{o}) = ext{sin}x, locate two intersection points on your graph. Label them:
Point A on the graph of -rac{1}{2} ext{cos}(x - 45^ ext{o}).
Point B on the graph of g(x).
Step 5
5.5 Use the graphs drawn in QUESTION 5.1 to determine the values of x for which f''(x) < 0.
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Answer
From the graph, identify the intervals where the second derivative of f(x) is negative. This is visually represented where the graph of f(x) is concave down. The regions found are:
xextin(45exto;225exto)extor(225exto;360exto)