Which of the following is a general solution of the equation sin 2x = -rac{1}{2}?
A - HSC - SSCE Mathematics Extension 1 - Question 11 - 2018 - Paper 1
Question 11
Which of the following is a general solution of the equation sin 2x = -rac{1}{2}?
A. x = nrac{π}{12} + (-1)^{n}rac{π}{12}
B. x = nrac{π}{2} + (-1)^{n}rac{π... show full transcript
Worked Solution & Example Answer:Which of the following is a general solution of the equation sin 2x = -rac{1}{2}?
A - HSC - SSCE Mathematics Extension 1 - Question 11 - 2018 - Paper 1
Step 1
Which of the following is a general solution of the equation sin 2x = -rac{1}{2}?
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Answer
To find the general solution for the equation sin(2x)=−21:
Identify the angles: The sine function equals −21 at specific angles. These angles are typically 67π and 611π in the range from 0 to 2π.
General form: The general solutions can be expressed as:
For 67π: x=127π+nπ (since sin has a period of π)
For 611π: x=1211π+nπ
Combine results: When combining these with the factor (−1)n due to periodicity, we arrive at the most comprehensive general solution format.
Thus, the answer is C: x=n2π+(−1)n12π where n is any integer.
Step 2
Which function, in terms of time t, could represent the motion of the particle?
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Answer
In simple harmonic motion, the general form of displacement can be expressed as:
Understanding displacement and velocity: Given the relation v2=n2(2kt−x2), we recognize that a typical solution is either a sine or cosine function.
Position function: The displacement function of a particle in harmonic motion can be expressed as a sine function:
Given the form resembles oscillatory motion, we can assume x(t)=Asin(nt+ϕ) where A is the amplitude and ϕ is the phase shift.
Evaluate options: Considering the given options:
A. x=kcos(nt) is valid but depends on the phase.
B. x=ksin(nt) fits well.
C. x=2kcos(nt)−k includes a constant adjustment.
D. x=2ksin(nt)+k does as well, but might need further analysis.
Thus, the most versatile choice in harmonic models, considering amplitude is B: x=ksin(nt).