1. The problem is to find the angle $\angle AOB$, not $\angle ACB$.\n\n2. To find $\angle AOB$, we need to understand the points $A$, $O$, and $B$ and their positions or vectors. Usually, $O$ is the vertex of the angle, and $A$ and $B$ are points on the rays forming the angle.\n\n3. The formula to find the angle between two vectors $\vec{OA}$ and $\vec{OB}$ is given by:\n$$\cos \theta = \frac{\vec{OA} \cdot \vec{OB}}{|\vec{OA}| |\vec{OB}|}$$\nwhere $\theta = \angle AOB$.\n\n4. Important rules:\n- The dot product $\vec{OA} \cdot \vec{OB}$ is calculated as $x_1x_2 + y_1y_2 + z_1z_2$ for vectors in 3D or $x_1x_2 + y_1y_2$ in 2D.\n- The magnitude $|\vec{OA}|$ is $\sqrt{x_1^2 + y_1^2 + z_1^2}$ or $\sqrt{x_1^2 + y_1^2}$.\n\n5. Once you calculate $\cos \theta$, find $\theta$ by taking the inverse cosine:\n$$\theta = \cos^{-1} \left( \frac{\vec{OA} \cdot \vec{OB}}{|\vec{OA}| |\vec{OB}|} \right)$$\n\n6. Without specific coordinates or vectors for points $A$, $O$, and $B$, this is the general method to find $\angle AOB$.\n\nIf you provide the coordinates or vectors, I can compute the exact angle for you.