The diagram below shows a wooden board ABCDE, which consists of an isosceles triangle ABC mounted on top of a rectangle ACDE. Given that AB = BC = 5 m, AE = 3 m and BM = x m. B 3 m 5 m xm I M (i) (ii) Show that dA dx (iii) E Show that the area of the wooden frame, 4, is given by A = (x+6)25 x. 25-6x-2x 25-x Find the value of x for which A has a stationary value. (iv) Find the stationary value of 4 and determine its nature of these stationary points.