The graphs below represent the curves of functions $f$ and $g$ defined by
$f(x) = a \, \sin x$ and $g(x) = - \cos b x$ respectively for $x \in [0 ; 180^\circ]$ - NSC Technical Mathematics - Question 5 - 2019 - Paper 2
Question 5
The graphs below represent the curves of functions $f$ and $g$ defined by
$f(x) = a \, \sin x$ and $g(x) = - \cos b x$ respectively for $x \in [0 ; 180^\circ]$.
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Worked Solution & Example Answer:The graphs below represent the curves of functions $f$ and $g$ defined by
$f(x) = a \, \sin x$ and $g(x) = - \cos b x$ respectively for $x \in [0 ; 180^\circ]$ - NSC Technical Mathematics - Question 5 - 2019 - Paper 2
Step 1
Give the period of $f$
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Answer
The period of the sine function f(x)=asinx is 360∘. Therefore, the period of f is 360.
Step 2
Determine the numerical values of $a$ and $b$
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Answer
From the graph, it can be observed that the maximum value of f(x) is 2, which suggests that a=−2. Also, the maximum value of g(x) is at 1, which suggests that b=2.
Step 3
Write down the coordinates of $T$
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Answer
The coordinates of point T can be determined from the graph as follows: T(158.5∘;−0.7).
Step 4
Determine the value(s) of $x$ for which:
g(x) \cdot f(x) > 0$ for $x \in [90^\circ ; 180^\circ]$
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Answer
The product g(x)⋅f(x)>0 holds true when both functions are either both positive or both negative. Analyzing the graph, this occurs for: 135∘<x<180∘.
Thus, x∈[135∘;180∘].
Step 5
Determine the value(s) of $x$ for which:
$f(x)$ will be undefined
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Answer
The function f(x) will be undefined specifically whenever the sine function oscillates. However, from the equation provided, we look for other points. Hence, x=45∘ or x=135∘.