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In die diagram is die grafiek van $f(x)= ext{cos}2x$ vir die interval $x ext{ } ext{ } [-270^ ext{°}; 90^ ext{°}]$ gesketst - NSC Mathematics - Question 6 - 2017 - Paper 2

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In-die-diagram-is-die-grafiek-van-$f(x)=-ext{cos}2x$-vir-die-interval-$x--ext{-}--ext{-}-[-270^-ext{°};-90^-ext{°}]$-gesketst-NSC Mathematics-Question 6-2017-Paper 2.png

In die diagram is die grafiek van $f(x)= ext{cos}2x$ vir die interval $x ext{ } ext{ } [-270^ ext{°}; 90^ ext{°}]$ gesketst. 6.1 Skets die grafiek van $g(x)=2 ext... show full transcript

Worked Solution & Example Answer:In die diagram is die grafiek van $f(x)= ext{cos}2x$ vir die interval $x ext{ } ext{ } [-270^ ext{°}; 90^ ext{°}]$ gesketst - NSC Mathematics - Question 6 - 2017 - Paper 2

Step 1

Skets die grafiek van $g(x)=2 ext{sin}x-1$

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Answer

To sketch the graph of the function g(x)=2extsinx1g(x) = 2 ext{sin}x - 1, we start by determining the key features of the sine function. The amplitude of this sine function is 2, meaning it oscillates between -1 and 1.

  1. Identify the Amplitude and Vertical Shift: The function oscillates between 11 and 3-3. The normal sine function y=extsinxy = ext{sin}x has values from -1 to 1, and with the transformation for g(x)g(x), we shift this down by 1 to get [1,3][-1, -3].

  2. Determine Intercepts and Shape: The intercept occurs at x=0x=0, with g(0)=1g(0) = -1.

  3. Plot Key Points: Find the points including the maximum at (90°,3)(-90°, -3) and similar steps can be taken for other key values such as 210°-210° and 30°30°.

  4. Draw the Graph: Connect the points smoothly to create a sinusoidal wave reflecting these transformations.

Step 2

Gestel $A$ is 'n snypunt van die grafieke van $f$ en $g$. Toon dat die $x$-koördinaat van $A$ die vergelyking $ ext{sin} x = - rac{1+ ext{√}5}{2}$ bevredig.

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To find the x-coordinate of point AA, we start from the equation derived from equalizing f(x)f(x) and g(x)g(x):

extcos2x=2extsinx1 ext{cos}2x = 2 ext{sin}x - 1 This can be rewritten in standard quadratic form: 12extsin2x2extsinx=01 - 2 ext{sin}^2x - 2 ext{sin}x = 0 Using the quadratic formula: ext{sin}x = rac{-b ext{±} ext{√}(b^2 - 4ac)}{2a} We substitute for a=2,b=2,c=1a=2, b=2, c=-1 and we find: ext{sin}x = - rac{1+ ext{√}5}{2}.

Step 3

Bereken vervolgens die koördinates van die snypunte van grafieke van $f$ en $g$ vir die interval $x ext{ } [-270^ ext{°}; 90^ ext{°}]$.

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To find the coordinates of the intersection points of ff and gg where xx is in the range [270°;90°][-270°; 90°]:

  1. Calculate the values: By solving ext{sin} x = - rac{1+ ext{√}5}{2}, we find two specific angles based on the sine values.

  2. Identify Reference Angles: Calculate the reference angles to find ext{sin}^{-1}ig(- rac{1+ ext{√}5}{2}ig) yielding approximate values.

  3. List Coordinates: The coordinates obtained are (38,17°;0,24)(38,17°; 0,24) and (218,17°;0,24)(-218,17°; 0,24) based on periodicity.

Thus, we conclude our results with the points of intersection.

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