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
Question 6
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)=2extsinx−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.
Identify the Amplitude and Vertical Shift: The function oscillates between 1 and −3. The normal sine function y=extsinx has values from -1 to 1, and with the transformation for g(x), we shift this down by 1 to get [−1,−3].
Determine Intercepts and Shape: The intercept occurs at x=0, with g(0)=−1.
Plot Key Points: Find the points including the maximum at (−90°,−3) and similar steps can be taken for other key values such as −210° and 30°.
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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Answer
To find the x-coordinate of point A, we start from the equation derived from equalizing f(x) and g(x):
extcos2x=2extsinx−1
This can be rewritten in standard quadratic form:
1−2extsin2x−2extsinx=0
Using the quadratic formula:
ext{sin}x = rac{-b ext{±} ext{√}(b^2 - 4ac)}{2a}
We substitute for a=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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Answer
To find the coordinates of the intersection points of f and g where x is in the range [−270°;90°]:
Calculate the values: By solving ext{sin} x = -rac{1+ ext{√}5}{2}, we find two specific angles based on the sine values.
Identify Reference Angles: Calculate the reference angles to find ext{sin}^{-1}ig(-rac{1+ ext{√}5}{2}ig) yielding approximate values.
List Coordinates: The coordinates obtained are (38,17°;0,24) and (−218,17°;0,24) based on periodicity.
Thus, we conclude our results with the points of intersection.