Irina uses a set of coordinate axes to draw her design of a window The base of the window is on the 2 axis the upper part of the window is in the form of a quadratic curve and the sides are vertical lines as shown on the diagram The curve has end points 0 10 and 8 10 and its vertex is 4 12 Distances are measured in centimetres The quadratic curve can be expressed in the form ya br c for 0 8 a Write down the value of c a ill Hence find the equation of the quadratic curve b Find the area of the shaded region In Irina s design