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Solve, for $0 heta < 360^ ext{o}$, the equation 9sin(θ + 60°) = 4 giving your answers to 1 decimal place - Edexcel - A-Level Maths Pure - Question 8 - 2014 - Paper 1

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Solve,-for-$0--heta-<-360^-ext{o}$,-the-equation--9sin(θ-+-60°)-=-4-giving-your-answers-to-1-decimal-place-Edexcel-A-Level Maths Pure-Question 8-2014-Paper 1.png

Solve, for $0 heta < 360^ ext{o}$, the equation 9sin(θ + 60°) = 4 giving your answers to 1 decimal place. You must show each step of your working. Solve, for $- e... show full transcript

Worked Solution & Example Answer:Solve, for $0 heta < 360^ ext{o}$, the equation 9sin(θ + 60°) = 4 giving your answers to 1 decimal place - Edexcel - A-Level Maths Pure - Question 8 - 2014 - Paper 1

Step 1

Solve, for $0 heta < 360^ ext{o}$, the equation 9sin(θ + 60°) = 4

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Answer

To solve the equation, we start with:

9extsin(heta+60exto)=49 ext{sin}( heta + 60^ ext{o}) = 4

Dividing both sides by 9: ext{sin}( heta + 60^ ext{o}) = rac{4}{9}

Next, we find the angle whose sine is rac{4}{9}:

heta + 60^ ext{o} = ext{sin}^{-1}igg( rac{4}{9}igg)\ heta + 60^ ext{o} ext{ is approximately } 26.3877^ ext{o}

To find other angles within the range, we can also use: heta + 60^ ext{o} = 180^ ext{o} - ext{sin}^{-1}igg( rac{4}{9}igg)\ heta + 60^ ext{o} = 180^ ext{o} - 26.3877^ ext{o}

Calculating this gives: heta+60extoextisapproximately153.6123exto heta + 60^ ext{o} ext{ is approximately } 153.6123^ ext{o}

Subtracting 60° from both results:

ightarrow heta ext{ is approximately } -33.6123^ ext{o} ext{ (not within range)}2.2. heta = 153.6123^ ext{o} - 60^ ext{o} ightarrow heta ext{ is approximately } 93.6123^ ext{o}$$

Now continuing with the other case: heta+60exto=360exto26.3877exto heta+60exto=333.6123exto heta + 60^ ext{o} = 360^ ext{o} - 26.3877^ ext{o} \ heta + 60^ ext{o} = 333.6123^ ext{o} Subtracting 60° again:

ightarrow heta ext{ is approximately } 273.6123^ ext{o} \ heta = 273.6^ ext{o} \ ext{(not within } 0 < heta < 360)$$ Thus, the answers in the correct range are: $$ heta ext{ approximately } 93.6^ ext{o} ext{ and } 326.4^ ext{o}$$

Step 2

Solve, for $- ext{π} < x < ext{π}$, the equation 2tan x − 3sin x = 0

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Answer

Starting with the equation:

2exttanx3extsinx=02 ext{tan}x - 3 ext{sin}x = 0

This can be rearranged as: 2exttanx=3extsinx2 ext{tan}x = 3 ext{sin}x

Recalling that ext{tan}x = rac{ ext{sin}x}{ ext{cos}x}, we substitute: 2 rac{ ext{sin}x}{ ext{cos}x} = 3 ext{sin}x

Dividing both sides by extsinx ext{sin}x (assuming extsinxeq0 ext{sin}x eq 0): rac{2}{ ext{cos}x} = 3

This simplifies to: ext{cos}x = rac{2}{3}

Now taking the inverse cosine: x = ext{cos}^{-1}igg( rac{2}{3}igg)\ x ext{ is approximately } 0.8411

The second solution in the range extπ<x<extπ- ext{π} < x < ext{π} can be found using: x = - ext{cos}^{-1}igg( rac{2}{3}igg)\ x ext{ is approximately } -0.8411

Thus the solutions are: xextapproximately0.84extand0.84x ext{ approximately } 0.84 ext{ and } -0.84

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