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In the diagram below, AB represents a vertical tower - NSC Technical Mathematics - Question 6 - 2019 - Paper 2

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In the diagram below, AB represents a vertical tower. Mpolokeng is standing at point C which is 150 m away from base B of the tower. The angle of elevation of A from... show full transcript

Worked Solution & Example Answer:In the diagram below, AB represents a vertical tower - NSC Technical Mathematics - Question 6 - 2019 - Paper 2

Step 1

6.1 Calculate the distance of AC.

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Answer

To calculate the distance AC, we can use the cosine function with respect to angle ACB:

extcos(50°)=150AC ext{cos}(50°) = \frac{150}{AC}

Rearranging gives:

AC=150cos(50°)AC = \frac{150}{\text{cos}(50°)}

Calculating:

AC1500.6428233.36extmAC \approx \frac{150}{0.6428} \approx 233.36 ext{ m}

Thus, the distance of AC is approximately 233.36 m.

Step 2

6.2 Hence, determine the size of β, if the area of △ACD = 3,3648 x 10^4 m².

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Answer

The area of triangle ACD can be expressed as:

Area=12AC×CD×sin(β)\text{Area} = \frac{1}{2} AC \times CD \times \text{sin}(β)

Given:

  • Area = 3,3648 x 10^4 m²
  • AC = 233.36 m
  • CD = 300 m

Setting up the equation:

3,3648x104=12×233.36×300×sin(β)3,3648 x 10^4 = \frac{1}{2} \times 233.36 \times 300 \times \text{sin}(β)

Solving for sin(β):

sin(β)=3,3648x104×2233.36×300\text{sin}(β) = \frac{3,3648 x 10^4 \times 2}{233.36 \times 300}

Calculating:

sin(β)0.96126157\text{sin}(β) \approx 0.96126157

Thus,

βarcsin(0.96126157)106°.β \approx \text{arcsin}(0.96126157) \approx 106°.

Step 3

6.3 Hence, determine the distance of AD.

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Answer

To find distance AD:

AD=AC+DC2imesACimesDCimesextcos(ACD)AD = AC + DC - 2 imes AC imes DC imes ext{cos}(∠ACD)

Substituting the known values:

  • AC = 233.36 m
  • DC = 300 m
  • ∠ACD = 106°

Calculating:

AD=233.36+3002imes233.36imes300imesextcos(106°)AD = 233.36 + 300 - 2 imes 233.36 imes 300 imes ext{cos}(106°)

Calculating:

AD1830.57056(233.36imes300imes0.275637)AD \approx 1830.57056 - (233.36 imes 300 imes -0.275637)

Simplifying yields:

AD427.84extm.AD \approx 427.84 ext{ m}.

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