Find the area of the purple shaded region

An elderly woman walked into the local country church. The friendly usher greeted her at the door and helped her up the flight of steps. "Where would you like to sit?" he asked politely. "The front row please." she answered. "You really don't want to do that", the usher said. "The pastor is really boring." "Do you happen to know who I am?" the woman inquired."No." he said. "I'm the pastor's mother," she replied indignantly. "Do you know who I am?" he asked. "No." she said. "Good," he answered.