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AB is 'n vertikale vlagpaal wat \( \sqrt{5p} \) meter lank is - NSC Mathematics - Question 7 - 2022 - Paper 2

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AB is 'n vertikale vlagpaal wat \( \sqrt{5p} \) meter lank is. AC en AD is twee kabels wat die vlagpaal anker. B, C en D is in dieselfde horisontale vlak. BD = 2p me... show full transcript

Worked Solution & Example Answer:AB is 'n vertikale vlagpaal wat \( \sqrt{5p} \) meter lank is - NSC Mathematics - Question 7 - 2022 - Paper 2

Step 1

7.1 Bepaal die lengte van AD in terme van p.

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Answer

To calculate the length of AD, we can apply Pythagoras' theorem. The relationship is given by:

AD2=AB2+BD2AD^2 = AB^2 + BD^2

Substituting the values:

AD2=(5p)2+(2p)2AD^2 = (\sqrt{5p})^2 + (2p)^2

This simplifies to:

AD2=5p+4p2AD^2 = 5p + 4p^2

So, we find that:

AD=5p+4p2=3pAD = \sqrt{5p + 4p^2} = 3p

Step 2

7.2 Toon dat die lengte van CD \( \frac{3p(sin(x) + cos(x))}{\sqrt{2}sin(x)} \).

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Answer

Using the sine rule on triangle ABC, we can express CD as follows:

CD=3psin(135x)sin(x)CD = \frac{3p}{sin(135^\circ - x)} \cdot sin(x)

Now, applying the compound angle formula, we have:

sin(135x)=sin(135)cos(x)cos(135)sin(x)sin(135^\circ - x) = sin(135^\circ)cos(x) - cos(135^\circ)sin(x)

Substituting the special values:

=3p(22cos(x)+22sin(x))sin(x)= \frac{3p \cdot (\frac{\sqrt{2}}{2}cos(x) + \frac{\sqrt{2}}{2}sin(x))}{sin(x)}

This further simplifies to:

CD=3p(2/2)(cos(x)+sin(x))sin(x)CD = \frac{3p(\sqrt{2}/2)(cos(x) + sin(x))}{sin(x)}

Thus, we have shown that:

CD=3p(sin(x)+cos(x))2sin(x)CD = \frac{3p(sin(x) + cos(x))}{\sqrt{2}sin(x)}

Step 3

7.3 Indien dit verder gegee word dat \( p = 10 \) en \( x = 110^\circ \), bereken die oppervlakte van \( \Delta ADC. \)

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Answer

To find the area of triangle ADC, we use the area formula:

Area=12(AD)(CD)sin(ACD)Area = \frac{1}{2} \cdot (AD)(CD) \cdot sin(\angle ACD)

Substituting the values we obtained:

=12(3p)(3p(sin(x)+cos(x))2sin(x))sin(45)= \frac{1}{2} \cdot (3p) \cdot \left( \frac{3p(sin(x) + cos(x))}{\sqrt{2}sin(x)} \right) \cdot sin(45^\circ)

With the values substituting for ( p = 10 ) and ( x = 110^\circ ):

=12(30)(3(10)(sin(110)+cos(110))2sin(110))22= \frac{1}{2} \cdot (30) \cdot \left( \frac{3(10)(sin(110^\circ) + cos(110^\circ))}{\sqrt{2}sin(110^\circ)} \right) \cdot \frac{\sqrt{2}}{2}

Calculating gives:

=143.11m2= 143.11 m^2

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