WJEC
Further Unit 4
2019
June
Q5
5. (a) Show that \(\sin \theta - \sin 3 \theta\) can be expressed in the form \(a \cos b \theta \sin \theta\), where \(a , b\) are integers whose values are to be determined.
(b) Find the mean value of \(y = 2 \cos 2 \theta \sin \theta + 7\) between \(\theta = 1\) and \(\theta = 3\), giving your answer correct to two decimal places.
WJEC
Further Unit 4
2019
June
Q7
7. (a) Write down the Maclaurin series expansion for \(\ln ( 1 - x )\) as far as the term in \(x ^ { 3 }\).
(b) Show that \(- 2 \ln \left( \frac { 1 - x } { ( 1 + x ) ^ { 2 } } \right)\) can be expressed in the form \(a x + b x ^ { 2 } + c x ^ { 3 } + \ldots\), where \(a , b , c\) are integers whose values are to be determined.
WJEC
Further Unit 4
2019
June
Q9
9. (a) Given that \(y = \sin ^ { - 1 } ( \cos \theta )\), where \(0 \leqslant \theta \leqslant \pi\), show that \(\frac { \mathrm { d } y } { \mathrm {~d} \theta } = k\), where the value of \(k\) is to be determined.
(b) Find the value of the gradient of the curve \(y = x ^ { 3 } \tan ^ { - 1 } 4 x\) when \(x = \frac { \pi } { 2 }\).
(c) Find the equation of the normal to the curve \(y = \tanh ^ { - 1 } ( 1 - x )\) when \(x = 1 \cdot 7\).
WJEC
Further Unit 4
2019
June
Q11
11. (a) Find the area of the region enclosed by the curve \(y = x \sinh x\), the \(x\)-axis and the lines \(x = 0\) and \(x = 1\).
(b) The region \(R\) is bounded by the curve \(y = \cosh 2 x\), the \(x\)-axis and the lines \(x = 0\) and \(x = 1\). Find the volume of the solid generated when \(R\) is rotated through four right-angles about the \(x\)-axis.
(c) Using your answer to part (b), find the total volume of the solid generated by rotating the region bounded by the curve \(y = \cosh 2 x\) and the lines \(x = - 1\) and \(x = 1\).
WJEC
Further Unit 4
2019
June
Q12
12. (a) Evaluate \(\int _ { 3 } ^ { 4 } \frac { 1 } { \sqrt { x ^ { 2 } - 4 } } \mathrm {~d} x\), giving your answer correct to three decimal places.
(b) Given that \(\int _ { 1 } ^ { 2 } \frac { k } { 9 - x ^ { 2 } } \mathrm {~d} x = \ln \frac { 25 } { 4 }\), find the value of \(k\).
(c) Show that \(\int \frac { ( \cosh x - \sinh x ) ^ { 3 } } { \cosh ^ { 2 } x + \sinh ^ { 2 } x - \sinh 2 x } \mathrm {~d} x\) can be expressed as \(- \mathrm { e } ^ { - x } + c\), where \(c\) is a constant.
WJEC
Further Unit 4
2022
June
Q9
9. (a) (i) Expand \(\left( \cos \frac { \theta } { 3 } + i \sin \frac { \theta } { 3 } \right) ^ { 3 }\).
(ii) Hence, by using de Moivre's theorem, show that \(\cos \theta\) can be expressed as
$$4 \cos ^ { 3 } \frac { \theta } { 3 } - 3 \cos \frac { \theta } { 3 }$$
(b) Hence, or otherwise, find the general solution of the equation \(\frac { \cos \theta } { \cos \frac { \theta } { 3 } } = 1\).
WJEC
Further Unit 4
2023
June
Q3
3. (a) Given that \(z = \cos \theta + \operatorname { isin } \theta\), use de Moivre's theorem to show that
$$z ^ { n } + \frac { 1 } { z ^ { n } } = 2 \cos n \theta$$
(b) Express \(32 \cos ^ { 6 } \theta\) in the form \(a \cos 6 \theta + b \cos 4 \theta + c \cos 2 \theta + d\), where \(a , b , c , d\) are integers whose values are to be determined.