OCR MEI C4 2013 June — Question 2 7 marks

Exam BoardOCR MEI
ModuleC4 (Core Mathematics 4)
Year2013
SessionJune
Marks7
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicStandard trigonometric equations
TypeConvert to quadratic in sin/cos
DifficultyStandard +0.3 This is a straightforward trigonometric equation requiring standard identities (cosec = 1/sin, cot = cos/sin) and manipulation to reach a given quadratic form, followed by routine solving of a quadratic and finding angles. The 'show that' structure provides the key step, making this slightly easier than average but still requiring multiple techniques.
Spec1.05h Reciprocal trig functions: sec, cosec, cot definitions and graphs1.05o Trigonometric equations: solve in given intervals

Show that the equation \(\cos ec x + 5 \cot x = 3 \sin x\) may be rearranged as $$3 \cos^2 x + 5 \cos x - 2 = 0.$$ Hence solve the equation for \(0° \leq x \leq 360°\), giving your answers to 1 decimal place. [7]

Question 2:
2
AnswerMarks Guidance
D90 B
C60
3030
0
0
AnswerMarks Guidance
3
–180 –1 50 –1
AnswerMarks Guidance
B30
A–60 C
–90
Question 2:
2
D | 90 | B
C | 60
30 | 30
0
0
– | 3
–1 | 80 –1 | 50 –1 | 20 –9 | 0 –6 | 0 –3 | 0 | 3 | 0 6 | 0 9 | 0 12 | 0 15 | 0 1 | 80
–
B | 30
A | –60 | C
–90
Show that the equation $\cos ec x + 5 \cot x = 3 \sin x$ may be rearranged as

$$3 \cos^2 x + 5 \cos x - 2 = 0.$$

Hence solve the equation for $0° \leq x \leq 360°$, giving your answers to 1 decimal place. [7]

\hfill \mbox{\textit{OCR MEI C4 2013 Q2 [7]}}