CAIE P1 2023 June — Question 6 6 marks

Exam BoardCAIE
ModuleP1 (Pure Mathematics 1)
Year2023
SessionJune
Marks6
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicRadians, Arc Length and Sector Area
TypeProving angle relationships
DifficultyStandard +0.3 This is a straightforward application of arc length and sector area formulas with basic trigonometry. Part (a) requires recognizing that the radius OA = x/cos(θ) from the right triangle, then applying arc length = rθ. Part (b) involves subtracting triangle area from sector area using standard formulas. The geometric setup is clear and the methods are routine for P1 level, making this slightly easier than average.
Spec1.03g Parametric equations: of curves and conversion to cartesian1.05d Radians: arc length s=r*theta and sector area A=1/2 r^2 theta

\includegraphics{figure_6} The diagram shows a sector \(OAB\) of a circle with centre \(O\). Angle \(AOB = \theta\) radians and \(OP = AP = x\).
  1. Show that the arc length \(AB\) is \(2x\theta \cos \theta\). [2]
  2. Find the area of the shaded region \(APB\) in terms of \(x\) and \(\theta\). [4]

Question 6:
AnswerMarks
6Recovery within working is allowed, e.g. a notation error in the working where the following line of working makes the candidate’s intent clear.
PMT
9709/12 Cambridge International AS & A Level – Mark Scheme May/June 2023
PUBLISHED
Abbreviations
AEF/OE Any Equivalent Form (of answer is equally acceptable) / Or Equivalent
AG Answer Given on the question paper (so extra checking is needed to ensure that the detailed working leading to the result is valid)
CAO Correct Answer Only (emphasising that no ‘follow through’ from a previous error is allowed)
CWO Correct Working Only
ISW Ignore Subsequent Working
SOI Seen Or Implied
SC Special Case (detailing the mark to be given for a specific wrong solution, or a case where some standard marking practice is to be varied in the
light of a particular circumstance)
WWW Without Wrong Working
AWRT Answer Which Rounds To
© UCLES 2023 Page 5 of 22
AnswerMarks Guidance
QuestionAnswer Marks

AnswerMarks
6(a)1 OA x
OA xcos or  or
2 sinπ2 sin
OA2  x2 x2 2x2cosπ2 or
AnswerMarks Guidance
x2 r2 x2 2rxcos or other valid method.*B1 1
Correct expression containing OA, OA or OA2(allow p,
2
a or r for OA) containing only terms with x and  but not
just OA2xcos .
Do not condone sinπ2 until missing brackets
recovered or cos(1802) until it becomes cos2 etc.
AnswerMarks Guidance
OA = 2xcos leading to Arc length = 2xcosDB1 AG Complete correct method showing all necessary
working. Condone 2xcos .
AnswerMarks
2If B0 but www then SCB1 for OA = 2xcos leading to
Arc length = 2xcos.

AnswerMarks
6(b)1
2xcos2
Sector area = θ
AnswerMarks Guidance
2M1 OE Using sector formula with a correct OA. Condone
cos2 for cos2 and missing brackets.
1 1
Triangle area = 2xcosxsin OR x2sinπ2
AnswerMarks Guidance
2 2M1 Using a correct triangle formula for the correct triangle.
Condone missing brackets and 180 for π.
AnswerMarks Guidance
[Area APB =] Their sector area – their triangle areaM1 Both expressions must be areas involving terms with x2 and
 only. Condone missing brackets and 180 for π for the
triangle. Condone calling the sector a segment.
1 1
[Area APB =] 2xcos2  x2sinπ2
2 2
1
[ x2(2cos2 sin2) or x2cos(2cos sin)]
AnswerMarks Guidance
2A1 OE
A correct expression. Mark the first unsimplified result of
subtraction and ISW any incorrect ‘simplifications’.
4
AnswerMarks Guidance
QuestionAnswer Marks
Question 6:
6 | Recovery within working is allowed, e.g. a notation error in the working where the following line of working makes the candidate’s intent clear.
PMT
9709/12 Cambridge International AS & A Level – Mark Scheme May/June 2023
PUBLISHED
Abbreviations
AEF/OE Any Equivalent Form (of answer is equally acceptable) / Or Equivalent
AG Answer Given on the question paper (so extra checking is needed to ensure that the detailed working leading to the result is valid)
CAO Correct Answer Only (emphasising that no ‘follow through’ from a previous error is allowed)
CWO Correct Working Only
ISW Ignore Subsequent Working
SOI Seen Or Implied
SC Special Case (detailing the mark to be given for a specific wrong solution, or a case where some standard marking practice is to be varied in the
light of a particular circumstance)
WWW Without Wrong Working
AWRT Answer Which Rounds To
© UCLES 2023 Page 5 of 22
Question | Answer | Marks | Guidance
--- 6(a) ---
6(a) | 1 OA x
OA xcos or  or
2 sinπ2 sin
OA2  x2 x2 2x2cosπ2 or
x2 r2 x2 2rxcos or other valid method. | *B1 | 1
Correct expression containing OA, OA or OA2(allow p,
2
a or r for OA) containing only terms with x and  but not
just OA2xcos .
Do not condone sinπ2 until missing brackets
recovered or cos(1802) until it becomes cos2 etc.
OA = 2xcos leading to Arc length = 2xcos | DB1 | AG Complete correct method showing all necessary
working. Condone 2xcos .
2 | If B0 but www then SCB1 for OA = 2xcos leading to
Arc length = 2xcos.
--- 6(b) ---
6(b) | 1
2xcos2
Sector area = θ
2 | M1 | OE Using sector formula with a correct OA. Condone
cos2 for cos2 and missing brackets.
1 1
Triangle area = 2xcosxsin OR x2sinπ2
2 2 | M1 | Using a correct triangle formula for the correct triangle.
Condone missing brackets and 180 for π.
[Area APB =] Their sector area – their triangle area | M1 | Both expressions must be areas involving terms with x2 and
 only. Condone missing brackets and 180 for π for the
triangle. Condone calling the sector a segment.
1 1
[Area APB =] 2xcos2  x2sinπ2
2 2
1
[ x2(2cos2 sin2) or x2cos(2cos sin)]
2 | A1 | OE
A correct expression. Mark the first unsimplified result of
subtraction and ISW any incorrect ‘simplifications’.
4
Question | Answer | Marks | Guidance
\includegraphics{figure_6}

The diagram shows a sector $OAB$ of a circle with centre $O$. Angle $AOB = \theta$ radians and $OP = AP = x$.

\begin{enumerate}[label=(\alph*)]
\item Show that the arc length $AB$ is $2x\theta \cos \theta$. [2]

\item Find the area of the shaded region $APB$ in terms of $x$ and $\theta$. [4]
\end{enumerate}

\hfill \mbox{\textit{CAIE P1 2023 Q6 [6]}}