The first period of the graph of \( y=\cos (x) \) starts at \( y= \) \( \qquad \) a 0 b -1 C 1 d \( \pi \) e \( 2 \pi \) Check It

To determine where the first period of the graph of \( y = \cos(x) \) starts, we need to understand the properties of the cosine function. 1. The cosine function \( y = \cos(x) \) has a maximum value of 1 and a minimum value of -1. 2. The function starts at its maximum value when \( x = 0 \), which means \( y = \cos(0) = 1 \). 3. The period of the cosine function is \( 2\pi \), meaning it repeats every \( 2\pi \) units. Given these points, the first period of the graph of \( y = \cos(x) \) starts at \( y = 1 \) when \( x = 0 \). Thus, the correct answer is: **C 1**