OCR MEI Further Pure Core AS 2020 November — Question 10 7 marks

Exam BoardOCR MEI
ModuleFurther Pure Core AS (Further Pure Core AS)
Year2020
SessionNovember
Marks7
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicVectors: Lines & Planes
TypeParallel and perpendicular planes
DifficultyChallenging +1.2 This is a Further Maths question requiring students to use three constraints (magnitude, angle with axis, parallel to plane) to find a unique vector. It involves standard techniques (dot product for angle, normal vector for plane condition) but requires careful coordination of multiple conditions and solving a system with a quadratic equation. More challenging than typical A-level questions but still follows established methods without requiring novel insight.
Spec1.10c Magnitude and direction: of vectors4.04c Scalar product: calculate and use for angles

10 A vector \(\mathbf { v }\) has magnitude 1 unit. The angle between \(\mathbf { v }\) and the positive \(z\)-axis is \(60 ^ { \circ }\), and \(\mathbf { v }\) is parallel to the plane \(x - 2 y = 0\). Given that \(\mathbf { v } = a \mathbf { i } + b \mathbf { j } + c \mathbf { k }\), where \(a , b\) and \(c\) are all positive, find \(\mathbf { v }\). \section*{END OF QUESTION PAPER}

Question 10:
AnswerMarks Guidance
10a2 + b2 + c2 = 1 B1
(ai+bj+ck).k
cos60°=
1× a2+b2+c2
1
⇒ c= a2 +b2 +c2
AnswerMarks
2M1
A13.1a
1.1oe, e.g. sin 30° = c/√(a2+b2+c2)
as line makes 30° angle with
Oxy plane
[so c = ½ ]
(ai + bj + ck).(i − 2j) = 0
AnswerMarks
⇒ a −2b = 0M1
A13.1a
1.1or equiv arguments
3 3
1
c= , b= , a=
AnswerMarks Guidance
2 20 5B2,1,0
[7]1.1, 3.1a oe or 0.387 or 0.775 or better
PPMMTT
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Question 10:
10 | a2 + b2 + c2 = 1 | B1 | 3.1a | soi
(ai+bj+ck).k
cos60°=
1× a2+b2+c2
1
⇒ c= a2 +b2 +c2
2 | M1
A1 | 3.1a
1.1 | oe, e.g. sin 30° = c/√(a2+b2+c2)
as line makes 30° angle with
Oxy plane
[so c = ½ ]
(ai + bj + ck).(i − 2j) = 0
⇒ a −2b = 0 | M1
A1 | 3.1a
1.1 | or equiv arguments
3 3
1
c= , b= , a=
2 20 5 | B2,1,0
[7] | 1.1, 3.1a | oe or 0.387 or 0.775 or better
PPMMTT
OCR (Oxford Cambridge and RSA Examinations)
The Triangle Building
Shaftesbury Road
Cambridge
CB2 8EA
OCR Customer Contact Centre
Education and Learning
Telephone: 01223 553998
Facsimile: 01223 552627
Email: general.qualifications@ocr.org.uk
www.ocr.org.uk
For staff training purposes and as part of our quality assurance programme your call may be
recorded or monitored
10 A vector $\mathbf { v }$ has magnitude 1 unit. The angle between $\mathbf { v }$ and the positive $z$-axis is $60 ^ { \circ }$, and $\mathbf { v }$ is parallel to the plane $x - 2 y = 0$.

Given that $\mathbf { v } = a \mathbf { i } + b \mathbf { j } + c \mathbf { k }$, where $a , b$ and $c$ are all positive, find $\mathbf { v }$.

\section*{END OF QUESTION PAPER}

\hfill \mbox{\textit{OCR MEI Further Pure Core AS 2020 Q10 [7]}}