Solve, for $0 \leq \theta \leq 180^{\circ}$,
$$2\cot^2(30^{\circ}) = 7\csc(30^{\circ}) - 5$$
Give your answers in degrees to 1 decimal place. - Edexcel - A-Level Maths Pure - Question 7 - 2012 - Paper 6
Question 7
Solve, for $0 \leq \theta \leq 180^{\circ}$,
$$2\cot^2(30^{\circ}) = 7\csc(30^{\circ}) - 5$$
Give your answers in degrees to 1 decimal place.
Worked Solution & Example Answer:Solve, for $0 \leq \theta \leq 180^{\circ}$,
$$2\cot^2(30^{\circ}) = 7\csc(30^{\circ}) - 5$$
Give your answers in degrees to 1 decimal place. - Edexcel - A-Level Maths Pure - Question 7 - 2012 - Paper 6
Step 1
Rewrite the equation with known values
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Answer
Since heta=30∘, we know that
cot(30∘)=31 and csc(30∘)=2
. We can substitute these values into the equation:
2(31)2=7(2)−5.
Step 2
Simplify the equation
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Answer
Now, simplifying both sides:
32=14−5
This leads to: 32=9, which is incorrect, indicating that we should derive solution for heta.
Step 3
Set up the equation cos(θ)
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Answer
We can reorder and form an equation:
2cot2(θ)=7csc(θ)−5
Substituting again:
2cot2(θ)=14−5=9
This will yield to finding heta.
Step 4
Solve for θ
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Answer
After reorganizing,
cot2(θ)=29
This leads to
θ=\arccot(23)
Calculate principal solution:
Using calculator, find:
θ≈53.5∘.
Also, check the domain and the possible secondary solution:
θ=180∘−53.5∘≈126.5∘.