) is x ; that is, = − ) . The tangent meets the x -axis at the point ( , ). The slope of the tangent is − . So the slope of the normal is and hence equation of the normal is y ) ; that is y and it passes through the origin.
The area to be found is shaded in the adjoining figure. It can be found by two methods. Method Viewing in the postive direction of y -axis, the required area is the area of the region bounded by x -axis, y and x . So it can be obtained by applying the formula ydx