Date | November 2013 | Marks available | 3 | Reference code | 13N.1.sl.TZ0.5 |
Level | SL only | Paper | 1 | Time zone | TZ0 |
Command term | Find | Question number | 5 | Adapted from | N/A |
Question
Let \(f(x) = \sin \left( {x + \frac{\pi }{4}} \right) + k\). The graph of f passes through the point \(\left( {\frac{\pi }{4},{\text{ }}6} \right)\).
Find the value of \(k\).
Find the minimum value of \(f(x)\).
Let \(g(x) = \sin x\). The graph of g is translated to the graph of \(f\) by the vector \(\left( {\begin{array}{*{20}{c}} p \\ q \end{array}} \right)\).
Write down the value of \(p\) and of \(q\).
Markscheme
METHOD 1
attempt to substitute both coordinates (in any order) into \(f\) (M1)
eg \(f\left( {\frac{\pi }{4}} \right) = 6,{\text{ }}\frac{\pi }{4} = \sin \left( {6 + \frac{\pi }{4}} \right) + k\)
correct working (A1)
eg \(\sin \frac{\pi }{2} = 1,{\text{ }}1 + k = 6\)
\(k = 5\) A1 N2
[3 marks]
METHOD 2
recognizing shift of \(\frac{\pi }{4}\) left means maximum at \(6\) R1)
recognizing \(k\) is difference of maximum and amplitude (A1)
eg \(6 - 1\)
\(k = 5\) A1 N2
[3 marks]
evidence of appropriate approach (M1)
eg minimum value of \(\sin x\) is \( - 1,{\text{ }} - 1 + k,{\text{ }}f'(x) = 0,{\text{ }}\left( {\frac{{5\pi }}{4},{\text{ }}4} \right)\)
minimum value is \(4\) A1 N2
[2 marks]
\(p = - \frac{\pi }{4},{\text{ }}q = 5{\text{ }}\left( {{\text{accept \(\left( \begin{array}{c} - {\textstyle{\pi \over 4}}\\5\end{array} \right)\)}}} \right)\) A1A1 N2
[2 marks]