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Date	May 2019	Marks available	2	Reference code	19M.2.SL.TZ1.S_8
Level	Standard Level	Paper	Paper 2	Time zone	Time zone 1
Command term	Find	Question number	S_8	Adapted from	N/A

Question

Let $f\left( x \right) = 2\,{\text{sin}}\left( {3x} \right) + 4$ for $x \in \mathbb{R}$ .

Let $g\left( x \right) = 5f\left( {2x} \right)$ .

The function $g$ can be written in the form $g\left( x \right) = 10\,{\text{sin}}\left( {bx} \right) + c$ .

The range of $f$ is $k$ ≤ $f\left( x \right)$ ≤ $m$ . Find $k$ and $m$ .

[3]

a.

Find the range of $g$ .

[2]

b.

Find the value of $b$ and of $c$ .

[3]

c.i.

Find the period of $g$ .

[2]

c.ii.

The equation $g\left( x \right) = 12$ has two solutions where $\pi$ ≤ $x$ ≤ ${\frac{{4\pi }}{3}}$ . Find both solutions.

[3]

d.

Markscheme

* This question is from an exam for a previous syllabus, and may contain minor differences in marking or structure.

valid attempt to find range (M1)

eg , max = 6 min = 2,

$2\,{\text{sin}}\left( {3 \times \frac{\pi }{6}} \right) + 4$ and $2\,{\text{sin}}\left( {3 \times \frac{\pi }{2}} \right) + 4$ , $2\left( 1 \right) + 4$ and $2\left( { - 1} \right) + 4$ ,

$k = 2$ , $m = 6$ A1A1 N3

[3 marks]

a.

10 ≤ $y$ ≤ 30 A2 N2

[2 marks]

b.

evidence of substitution (may be seen in part (b)) (M1)

eg $5\left( {2\,{\text{sin}}\left( {{\text{3}}\left( {2x} \right)} \right) + 4} \right)$ , ${{\text{3}}\left( {2x} \right)}$

$b = 6$ , $c = 20$ (accept $10\,{\text{sin}}\left( {6x} \right) + 20$ ) A1A1 N3

Note: If no working shown, award N2 for one correct value.

[3 marks]

c.i.

correct working (A1)

eg $\frac{{2\pi }}{b}$

1.04719

$\frac{{2\pi }}{6}\,\,\,\left( { = \frac{\pi }{3}} \right)$ , 1.05 A1 N2

[2 marks]

c.ii.

valid approach (M1)

eg , ${\text{si}}{{\text{n}}^{ - 1}}\left( { - \frac{8}{{10}}} \right){\text{, }}6x = - 0.927{\text{, }} - 0.154549{\text{, }}x = 0.678147$

Note: Award M1 for any correct value for $x$ or $6x$ which lies outside the domain of $f$ .

3.81974, 4.03424

$x = 3.82$ , $x = 4.03$ (do not accept answers in degrees) A1A1 N3

[3 marks]

d.

Examiners report

[N/A]

a.

[N/A]

b.

[N/A]

c.i.

[N/A]

c.ii.

[N/A]

d.

Syllabus sections

Topic 3— Geometry and trigonometry » SL 3.7—Circular functions: graphs, composites, transformations

Show 89 related questions

19M.2.SL.TZ1.S_8c.i:
Find the value of $b$ and of $c$ .
SPM.2.SL.TZ0.9a:
Find the period of $f$ .
22M.2.SL.TZ2.8b:
Find the values of $t$ when $h_{A} (t) = h_{B} (t)$ .
EXM.3.AHL.TZ0.5a.iii:
Write down the period of this graph
18M.2.SL.TZ1.S_10a:
Find the coordinates of A.
18M.2.SL.TZ1.S_10b.i:
For the graph of $f$ , write down the amplitude.
19M.2.AHL.TZ1.H_10a:
Write down the maximum and minimum value of $v$ .
17M.2.SL.TZ2.S_4c:
Use the model to find the depth of the water 10 hours after high tide.
19M.2.SL.TZ1.S_8b:
Find the range of $g$ .
17N.2.SL.TZ0.S_10a:
Show that $f(2\pi ) = 2\pi$ .
19M.2.AHL.TZ1.H_10c:
Sketch the graph of $y = p\left( t \right)$ for 0 ≤ $t$ ≤ 0.02 , showing clearly the coordinates of the first maximum and the first minimum.
EXM.3.AHL.TZ0.5f.ii:
Show that $\frac{a}{b} = {\text{tan}}\,\theta$ .
17M.2.SL.TZ1.S_8a.i:
How much time is there between the first low tide and the next high tide?
EXM.3.AHL.TZ0.5c.ii:
Comment on your answer to part (c)(i).
EXM.3.AHL.TZ0.5e.i:
$A$ .
EXM.3.AHL.TZ0.5b.ii:
Find the value of $C$ .
17N.2.SL.TZ0.S_10d:
A saw has a toothed edge which is 300 mm long. Find the number of complete teeth on this saw.
EXM.3.AHL.TZ0.5e.iii:
$C$ .
18M.2.SL.TZ1.S_10e:
Find the first time when the ball’s speed is changing at a rate of 2 cm s⁻².
19M.1.AHL.TZ2.H_9a:
Find the $x$ -coordinates of the points of intersection of the two graphs.
19M.2.AHL.TZ1.H_10d:
Find the total time in the interval 0 ≤ $t$ ≤ 0.02 for which $p\left( t \right)$ ≥ 3.
17M.2.SL.TZ1.S_8a.ii:
Find the difference in height between low tide and high tide.
17N.2.SL.TZ0.S_10b.ii:
Find the equation of $L$ .
18M.2.SL.TZ1.S_10d:
Find the maximum speed of the ball.
19M.2.AHL.TZ1.H_10g:
Given that $p\left( t \right)$ can be written as $p\left( t \right) = a\,{\text{sin}}\left( {b\left( {t - c} \right)} \right) + d$ where $a$ , $b$ , $c$ , $d$ > 0, use your graph to find the values of $a$ , $b$ , $c$ and $d$ .
EXM.3.AHL.TZ0.5a.i:
Sketch the graph $y = 3\,{\text{sin}}\,x + 4\,{\text{cos}}\,x$ , for $- 2\pi \leqslant x \leqslant 2\pi$
16N.2.SL.TZ0.S_10a:
(i) Find the value of $c$ .

(ii) Show that $b = \frac{\pi }{6}$ .

(iii) Find the value of $a$ .
19M.1.SL.TZ2.S_7b:
Consider the graph of $g\left( x \right) = 2\,{\text{sin}}\,px$ , 0 ≤ $x$ < $2\pi$ , where $p$ > 0.

Find the greatest value of $p$ such that the graph of $g$ does not intersect the line $y = - 1$ .
EXM.3.AHL.TZ0.5c.i:
Find ${\text{arctan}}\frac{3}{4}$ , giving the answer to 3 significant figures.
EXM.3.AHL.TZ0.5g:
Hence prove your conjectures in part (e).
17N.2.SL.TZ0.S_10b.i:
Find the coordinates of ${{\text{P}}_0}$ and of ${{\text{P}}_1}$ .
22M.1.SL.TZ1.6b:
The $y$ -intercept of the graph of $g$ is at $(0, r)$ .

Given that $g (x) \geq 7$ , find the smallest value of $r$ .
EXN.1.SL.TZ0.9b:
Find the minimum height of the ball above the ground.
EXN.1.SL.TZ0.9d:
For the first 2 seconds of its motion, determine the amount of time that the ball is less than $1.8 + 0.2 \sqrt{2}$ metres above the ground.
17N.2.SL.TZ0.S_10c:
Show that the distance between the $x$ -coordinates of ${{\text{P}}_k}$ and ${{\text{P}}_{k + 1}}$ is $2\pi$ .
19M.2.AHL.TZ1.H_10b:
Write down two transformations that will transform the graph of $y = v\left( t \right)$ onto the graph of $y = i\left( t \right)$ .
22M.2.AHL.TZ2.10b:
Find the values of $t$ when $h_{A} (t) = h_{B} (t)$ .
20N.2.SL.TZ0.S_8a.iii:
Hence find the number of rotations the water wheel makes in one hour.
EXM.3.AHL.TZ0.5b.i:
Use your answers from part (a) to write down the value of $A$ , $B$ and $D$ .
20N.2.SL.TZ0.S_8b:
Find $k$ .
20N.2.SL.TZ0.S_8d:
Determine the rate of change of $h$ when the top of the bucket is at $B$ .
EXM.3.AHL.TZ0.5f.i:
Show that $\frac{b}{{\sqrt {{a^2} + {b^2}} }} = {\text{cos}}\,\theta$ .
19M.2.SL.TZ1.S_8d:
The equation $g\left( x \right) = 12$ has two solutions where $\pi$ ≤ $x$ ≤ ${\frac{{4\pi }}{3}}$ . Find both solutions.
18M.2.SL.TZ1.S_10b.ii:
For the graph of $f$ , write down the period.
19M.1.AHL.TZ2.H_9c:
At the points A and B on the diagram, the gradients of the two graphs are equal.

Determine the $y$ -coordinate of A on the graph of $g$ .
17M.2.SL.TZ2.S_4a:
Find the value of $p$ .
SPM.2.SL.TZ0.9b.ii:
Hence, find the value of $f$ (6).
21M.1.SL.TZ2.8a:
Find the $x$ -coordinates of $A$ and $B$ .
19M.1.AHL.TZ2.H_9b:
Find the exact area of the shaded region, giving your answer in the form $p\pi + q\sqrt 3$ , where $p$ , $q \in \mathbb{Q}$ .
17M.2.SL.TZ1.S_8b.ii:
Find the value of $q$ ;
SPM.2.SL.TZ0.9b.i:
Find the value of $b$ .
EXN.1.SL.TZ0.9a:
Find the height of the ball above the ground when it is released.
EXN.1.SL.TZ0.9c:
Show that the ball takes $2$ seconds to return to its initial height above the ground for the first time.
20N.2.SL.TZ0.S_8c:
Find $A \hat{O} B$ .
19M.2.AHL.TZ1.H_10e:
Find ${p_{av}}$ (0.007).
20N.2.SL.TZ0.S_8a.ii:
Calculate the number of seconds it takes for the water wheel to complete one rotation.
20N.2.SL.TZ0.S_8a.i:
Find the height of point $A$ above the ground.
19M.2.AHL.TZ1.H_10f:
With reference to your graph of $y = p\left( t \right)$ explain why ${p_{av}}\left( T \right)$ > 0 for all $T$ > 0.
17M.2.SL.TZ2.S_4b:
Find the value of $q$ .
19M.2.SL.TZ1.S_8a:
The range of $f$ is $k$ ≤ $f\left( x \right)$ ≤ $m$ . Find $k$ and $m$ .
21M.2.SL.TZ2.7d:
Find the value of $p$ and the value of $q$ .
16N.2.SL.TZ0.S_10c:
(i) Find $w$ .

(ii) Hence or otherwise, find the maximum positive rate of change of $g$ .
21M.2.SL.TZ2.7e:
If the observer stands directly under point $C$ for one minute, point $D$ will pass over his head $n$ times.

Find the value of $n$ .
21N.2.SL.TZ0.8a:
Show that $b = \frac{π}{6}$ .
21N.2.SL.TZ0.8c:
Find the value of $d$ .
21N.2.SL.TZ0.8d:
Find the smallest possible value of $c$ .
22M.1.SL.TZ1.6a:
Describe these two transformations.
21N.2.SL.TZ0.8b:
Find the value of $a$ .
21N.2.AHL.TZ0.9a:
Show that $b = \frac{π}{6}$ .
21N.2.AHL.TZ0.9b:
Find the value of $a$ .
21N.2.AHL.TZ0.9d:
Find the smallest possible value of $c$ .
EXM.3.AHL.TZ0.5a.ii:
Write down the amplitude of this graph
EXM.3.AHL.TZ0.5d:
By considering the graph of $y = 5\,{\text{sin}}\,x + 12\,{\text{cos}}\,x$ , find the value of $A$ , $B$ , $C$ and $D$ .
18M.2.SL.TZ1.S_10c:
Hence, write $f\left( x \right)$ in the form $p\,\,{\text{cos}}\,\left( {x + r} \right)$ .
17M.2.SL.TZ1.S_8b.i:
Find the value of $p$ ;
EXM.3.AHL.TZ0.5e.ii:
$B$ .
EXM.3.AHL.TZ0.5e.iv:
$D$ .
17M.2.SL.TZ1.S_8b.iii:
Find the value of $r$ .
17M.2.SL.TZ1.S_8c:
There are two high tides on 12 December 2017. At what time does the second high tide occur?
16N.2.SL.TZ0.S_10b:
(i) Write down the value of $k$ .

(ii) Find $g(x)$ .
SPM.2.SL.TZ0.9d:
Find the value of $x$ for which the functions have the greatest difference.
SPM.2.SL.TZ0.9c:
Find the value of $p$ and the value of $q$ .
21M.2.SL.TZ1.4:
A Ferris wheel with diameter $110$ metres rotates at a constant speed. The lowest point on the wheel is $10$ metres above the ground, as shown on the following diagram. $P$ is a point on the wheel. The wheel starts moving with $P$ at the lowest point and completes one revolution in $20$ minutes.

The height, $h$ metres, of $P$ above the ground after $t$ minutes is given by $h (t) = a \cos (b t) + c$ , where $a, b, c \in ℝ$ .

Find the values of $a$ , $b$ and $c$ .
21N.2.AHL.TZ0.9e:
Find the height of the water at $12 : 00$ .
21N.2.SL.TZ0.8e:
Find the height of the water at $12 : 00$ .
21N.2.SL.TZ0.8f:
Determine the number of hours, over a 24-hour period, for which the tide is higher than $5$ metres.
21N.2.AHL.TZ0.9c:
Find the value of $d$ .
21N.2.AHL.TZ0.9f:
Determine the number of hours, over a 24-hour period, for which the tide is higher than $5$ metres.
21N.2.AHL.TZ0.9g:
A fisherman notes that the water height at nearby Folkestone harbour follows the same sinusoidal pattern as that of Dungeness harbour, with the exception that high tides (and low tides) occur $50$ minutes earlier than at Dungeness.

Find a suitable equation that may be used to model the tidal height of water at Folkestone harbour.

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Topic 3— Geometry and trigonometry » SL 3.8—Solving trig equations

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