How can i check if the quad is backface on camera?

I want to detect if my quad mesh is back turned to camera. I think renderer.isVisible won’t work for this(because i couldn’t). thanks for your advices

Vector3 normal = …; // The normal of your quad. You may need to loop through the mesh normals Unity - Scripting API: Mesh.normals
Vector3 cameraForward = …; // Camera.main.transform.forward for instance
bool isNormalFacingCamera = Vector3.Dot(normal, cameraForward) > 0;