3 (12 marks) Use a SEPARATE writing booklet - HSC - SSCE Mathematics Extension 1 - Question 3 - 2004 - Paper 1
Question 3
3 (12 marks) Use a SEPARATE writing booklet.
(a) Find \( \int \cos 4x \, dx \) :
(b) Let \( P(x) = (x + 1)(x - 3)Q(x) + a(x + 1) + b \), where \( Q(x) \) is a poly... show full transcript
Worked Solution & Example Answer:3 (12 marks) Use a SEPARATE writing booklet - HSC - SSCE Mathematics Extension 1 - Question 3 - 2004 - Paper 1
Step 1
Find \( \int \cos 4x \, dx \) :
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Answer
To find the integral, we can use the formula for the integral of cosine:
∫cos(kx)dx=k1sin(kx)+C
For ( k = 4 ):
∫cos4xdx=41sin4x+C
Step 2
What is the value of \( b \) ?
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Answer
To find ( b ), we can utilize the information that when ( P(x) ) is divided by ( (x + 1) ), the remainder is -11:
What is the remainder when \( P(x) \) is divided by \( (x + 1)(x - 3) \) ?
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Answer
Using the Remainder Theorem, we know the remainders found from dividing by the factors:\
For ( (x + 1) ), remainder is -11,
For ( (x - 3) ), remainder is 1.
Thus, the remainder when dividing by ( (x + 1)(x - 3) ) can be expressed as:
( R(x) = Ax + B ) and substituting both conditions will help find A and B.
Step 4
Find an expression for \( x \) in terms of \( h \).
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Answer
From the relationship in the right triangle formed, we can apply Pythagoras' theorem:
x2+h2=16
Thus, solving for ( x ):
x=16−h2
Step 5
At what rate is the pontoon moving away from the jetty?
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Answer
Using related rates, we differentiate the expression for ( x ):
dtdx=2(16−h2)211(−2hdtdh)
Then substitute ( h = -1 ) and ( \frac{dh}{dt} = 0.3 \text{ m/h} ) to find ( \frac{dx}{dt} ).
Step 6
Explain why \( \angle FAC = 60^\circ \).
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Answer
The geometry of the figure indicates that triangle ( FAC ) is equilateral as all sides are equal; hence, all angles, including ( \angle FAC ), measure 60 degrees.
Step 7
Show that \( FO = \sqrt{6} \) metres.
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Answer
In the right triangle formed by the center O, point F and line segment AC:
Using the coordinates: Each edge being 2 meters, calculate the lengths:
FO=AO2+AF2=22+22=4+2=6 m.
Step 8
Calculate the size of \( \angle XYF \) to the nearest degree.
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Answer
Using trigonometry: The relationship between angles ensures that we can apply the tangent function:
tan(∠XYF)=FYXY=61
Solving gives the angle as:\n Calculate the angle using Inverse Tangent function and round to the nearest degree.