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In the diagram, the graphs of $f(x) = ext{sin} x - 1$ and $g(x) = ext{cos} 2x$ are drawn for the interval $x ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } [ -90^{ ext{o}} ; 360^{ ext{o}} ]$ - NSC Mathematics - Question 6 - 2019 - Paper 2

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Question 6

In-the-diagram,-the-graphs-of---$f(x)-=--ext{sin}-x---1$-and-$g(x)-=--ext{cos}-2x$-are-drawn-for-the-interval---$x--ext{-}--ext{-}--ext{-}--ext{-}--ext{-}--ext{-}--ext{-}--ext{-}--ext{-}--ext{-}--ext{-}-[--90^{-ext{o}}-;-360^{-ext{o}}-]$-NSC Mathematics-Question 6-2019-Paper 2.png

In the diagram, the graphs of $f(x) = ext{sin} x - 1$ and $g(x) = ext{cos} 2x$ are drawn for the interval $x ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } e... show full transcript

Worked Solution & Example Answer:In the diagram, the graphs of $f(x) = ext{sin} x - 1$ and $g(x) = ext{cos} 2x$ are drawn for the interval $x ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } [ -90^{ ext{o}} ; 360^{ ext{o}} ]$ - NSC Mathematics - Question 6 - 2019 - Paper 2

Step 1

6.1 Write down the range of f.

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Answer

The range of the function f(x)=extsinx1f(x) = ext{sin} x - 1 can be determined by considering the range of extsinx ext{sin} x, which is [1,1][-1, 1]. Therefore, the range of f(x)f(x) is:
[2,0]extOR[2extand0][-2, 0] ext{ OR } [2 ext{ and } 0].

Step 2

6.2 Write down the values of x in the interval x ∈ [-90°, 360°] for which graph f is decreasing.

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Answer

The function f(x)f(x) is decreasing in the intervals where its derivative is negative. For the interval [90exto;270exto][-90^{ ext{o}}; 270^{ ext{o}}], the function f(x)f(x) is decreasing in the ranges:
90exto<x<270exto90^{ ext{o}} < x < 270^{ ext{o}}.

Step 3

6.3 Determine the value(s) of x for which PQ will be a maximum.

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Answer

To find the maximum of segment PQ, we set up the equation based on the intersection of PQPQ and the graphs of ff and gg:
PQ=extcos2x(extsinx1)PQ = ext{cos} 2x - ( ext{sin} x - 1)
This simplifies to:
PQ=12extsinxextsinx+1PQ = 1 - 2 ext{sin} x - ext{sin} x + 1
Setting into formula:
ext{sin} x = rac{-1}{2}
Thus,
x=194.48extoextor345.52extox = 194.48^{ ext{o}} ext{ or } 345.52^{ ext{o}}.

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