Given the functions defined by
$f(x) = ext{cos}(x - 45^ ext{o})$ and $g(x) = -2 ext{sin}(x)$, where $x ext{ is in } [0^ ext{o}, 360^ ext{o}]$
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 $x ext{ is in } [0^ ext{o}, 360^ ext{o}]$
5.1 Draw sketch... 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 $x ext{ is in } [0^ ext{o}, 360^ ext{o}]$
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 graph of $f$ and $g$
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Answer
To sketch the graphs of ( f(x) ) and ( g(x) ), we need to determine their characteristics:
Graph of ( f(x) = \text{cos}(x - 45^\circ) ):
Amplitude: 1
Period: 360°
X-intercepts: Occurs when ( f(x) = 0 ), which is at ( x = 45^\circ + 90n ) for integers ( n )
Turning Points: Maximum at ( x = 0^\circ ) and Minimum at ( x = 180^\circ )
Graph of ( g(x) = -2\text{sin}(x) ):
Amplitude: 2
Period: 360°
X-intercepts: Occurs when ( g(x) = 0 ), which happens at ( x = 0^\circ, 180^\circ, \text{ and } 360^\circ )
Minimum: At ( 90^\circ )
Both graphs should be plotted on the same set of axes, indicating turning points, intercepts and any end-points clearly.
Step 2
5.2 Write down the value of $x$ for which $g$ is a minimum.
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Answer
The function ( g(x) ) reaches its minimum value at ( x = 90^\circ ).
Step 3
5.3 Write down the period of $g$.
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Answer
The period of the function ( g(x) ) is 360°.
Step 4
5.4 Use the letters A and B to indicate on the graphs where $rac{1}{2} ext{cos}(x - 45^ ext{o}) = ext{sin}(x)$.
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Answer
To solve for where ( \frac{1}{2} \text{cos}(x - 45^\circ) = \text{sin}(x) ), mark the intersection points on the graph as:
Point A: Intersection graphically at ( x > 45^\circ )
Point B: Intersection graphically at ( x < 225^\circ )
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 of ( f(x) ), ( f''(x) < 0 ) in the intervals where the graph is concave down, which occurs:
For ( 45^\circ < x < 225^\circ )
In other words, between the critical values of ( 45^\circ ) and ( 225^\circ ).