Triangle is looking jaggy.

Hi, i am drawing a triangle using code below. I am applying DoubleSided shader. Triangle is being rendered very close to camera. Triangle is looking jaggy

How can i make this triangle to look smoother ?

             Mesh mesh = gameObject1.GetComponent<MeshFilter>().mesh;
     mesh.Clear(false);
     mesh.vertices = new Vector3[] { yMinWorld ,     mouthPos , yMaxWorld } ;
     mesh.uv = new Vector2[] {new Vector2 (0.1f, 0.1f), new Vector2 (0.9f,0.1f), new Vector2 (0.5f, 0.9f) }; 
     mesh.triangles = new int[] {0, 1, 2} ;
     mesh.RecalculateNormals() ;