Find all the values of $\theta$, where $0^\circ \leq \theta \leq 360^\circ$, such that
$$ \sin(\theta - 60^\circ) = \frac{\sqrt{3}}{2} - HSC - SSCE Mathematics Advanced - Question 20 - 2023 - Paper 1
Question 20
Find all the values of $\theta$, where $0^\circ \leq \theta \leq 360^\circ$, such that
$$ \sin(\theta - 60^\circ) = \frac{\sqrt{3}}{2}. $$
Worked Solution & Example Answer:Find all the values of $\theta$, where $0^\circ \leq \theta \leq 360^\circ$, such that
$$ \sin(\theta - 60^\circ) = \frac{\sqrt{3}}{2} - HSC - SSCE Mathematics Advanced - Question 20 - 2023 - Paper 1
Step 1
Recognises that $\sin 60^\circ = \frac{\sqrt{3}}{2}$
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Answer
To find the values of θ such that
sin(θ−60∘)=23,
we utilize the fact that this means we need to determine the angles where the sine function yields 23. The principal angle for this value is 60∘.
Step 2
$\theta - 60^\circ = 60^\circ$
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Answer
By setting the equation as:
θ−60∘=60∘
we can solve for θ:
θ=60∘+60∘=120∘.
Step 3
$\theta - 60^\circ = 120^\circ$
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Answer
Additionally, since the sine function is positive in both the first and second quadrants, we can also set:
θ−60∘=120∘
This gives:
θ=120∘+60∘=180∘.
Step 4
$\theta - 60^\circ = 240^\circ$
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Answer
Further, because sine is also positive for the angle 240∘ in the third quadrant, we can also set:
θ−60∘=240∘
Solving gives:
θ=240∘+60∘=300∘.
Step 5
Final Results
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Answer
Thus, the final values of θ that satisfy the original equation are:
θ=120∘,300∘,360∘.