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Given the functions defined by $f(x) = ext{sin } x$ and g(x) = ext{cos } 2x, ext{ where } x ext{ in } [0^{ heta}; 180^{ heta}] 5.1 Write down the period of g - NSC Technical Mathematics - Question 5 - 2022 - Paper 2

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Given-the-functions-defined-by---$f(x)-=--ext{sin-}-x$---and---g(x)-=--ext{cos-}-2x,--ext{-where-}-x--ext{-in-}-[0^{-heta};-180^{-heta}]---5.1-Write-down-the-period-of-g-NSC Technical Mathematics-Question 5-2022-Paper 2.png

Given the functions defined by $f(x) = ext{sin } x$ and g(x) = ext{cos } 2x, ext{ where } x ext{ in } [0^{ heta}; 180^{ heta}] 5.1 Write down the period ... show full transcript

Worked Solution & Example Answer:Given the functions defined by $f(x) = ext{sin } x$ and g(x) = ext{cos } 2x, ext{ where } x ext{ in } [0^{ heta}; 180^{ heta}] 5.1 Write down the period of g - NSC Technical Mathematics - Question 5 - 2022 - Paper 2

Step 1

5.1 Write down the period of g.

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Answer

The period of the function g(x)=cos2xg(x) = \cos{2x} can be found using the formula for the period of cosine functions, which is given by:

extPeriod=2πb ext{Period} = \frac{2\pi}{|b|}

In this case, b=2b = 2, so:

extPeriod=2π2=π ext{Period} = \frac{2\pi}{2} = \pi

However, since we are asked for the period in degrees:

πextradians=180\pi ext{ radians} = 180^{\circ}

Thus, the period of gg is 180180^{\circ}.

Step 2

5.2 Draw sketch graphs of f and g on the same set of axes on the grid provided in the ANSWER BOOK.

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Answer

To sketch the graphs of f(x)=sinxf(x) = \sin{x} and g(x)=cos2xg(x) = \cos{2x}:

  1. Graph of f(x)=sinxf(x) = \sin{x}:

    • The sine function oscillates between -1 and 1.
    • It has a period of 360360^{\circ}.
    • The turning points occur at x=0,90,180,270,360x = 0^{\circ}, 90^{\circ}, 180^{\circ}, 270^{\circ}, 360^{\circ} with corresponding yy values, respectively, being 0,1,0,1,00, 1, 0, -1, 0.
    • The graph will start at the origin, peak at 9090^{\circ}, cross at 180180^{\circ}, trough at 270270^{\circ}, and return to the axis at 360360^{\circ}.
  2. Graph of g(x)=cos2xg(x) = \cos{2x}:

    • This cosine function also oscillates between -1 and 1 but has a period of 180180^{\circ}, due to the factor of 2.
    • The key points occur at 0,90,1800^{\circ}, 90^{\circ}, 180^{\circ}, with the values 1,0,11, 0, -1 at these points, respectively.
    • The graph starts at its maximum, crosses the axis at 9090^{\circ}, and reaches its minimum at 180180^{\circ}.

Make sure to label all turning points, endpoints, and intercepts on the axes.

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