To identify the phase shift and write the appropriate equation for the sine function, we need to analyze the options given.
Recall that the general form of a sine function is:
\[ f(x) = a \sin(b(x - c)) + d \]
where:
- \( c \) represents the phase shift,
- \( a \) is the amplitude,
- \( b \) affects the period (period = \( \frac{2\pi}{|b|} \)),
- \( d \) is the vertical shift.
From the responses provided, we can summarize the functions:
- \( f(x) = \sin(x + \pi) \)
- \( f(x) = \sin(x - \frac{\pi}{2}) \)
- \( f(x) = \sin x + \frac{\pi}{2} \) (not a phase shift, this is a vertical shift)
- \( f(x) = \sin(x + \frac{\pi}{2}) \)
To find the phase shift \( c \):
- Option 1: \( x + \pi \) indicates a phase shift of \( -\pi \).
- Option 2: \( x - \frac{\pi}{2} \) indicates a phase shift of \( \frac{\pi}{2} \).
- Option 3: This option does not apply since it is a vertical shift.
- Option 4: \( x + \frac{\pi}{2} \) indicates a phase shift of \( -\frac{\pi}{2} \).
Among these options, we can deduce that the correct identification of the phase shift corresponds to option 2, which gives a phase shift of \( \frac{\pi}{2} \).
Final Answer:
Therefore, the value of the phase shift \( c \) is \( \frac{\pi}{2} \), and the equation of the function is:
\[ f(x) = \sin\left(x - \frac{\pi}{2}\right) \]