1. The problem asks us to find an expression for the function $f(x)$ in the form $f(x) = a \cdot \sin(x)$ or $f(x) = a \cdot \cos(x)$ where $a$ is an integer. 2. To determine $a$, we need information about the graph such as amplitude, period, or specific points. Since the graph is not provided here, we assume the amplitude $a$ is the maximum absolute value of $f(x)$. 3. The general forms are: - $f(x) = a \cdot \sin(x)$ where the amplitude is $|a|$ - $f(x) = a \cdot \cos(x)$ where the amplitude is $|a|$ 4. Without additional data, the simplest assumption is $a=1$, so $f(x) = \sin(x)$ or $f(x) = \cos(x)$. 5. If the graph shows a sine wave starting at zero, use $f(x) = \sin(x)$. If it starts at maximum, use $f(x) = \cos(x)$. Final answer: $$f(x) = \sin(x)$$ or $$f(x) = \cos(x)$$ depending on the graph's phase.