5. of PQRS. In the diagram below, the graph of the function f(x)=8-x³ for * 20 and y 20 is represented. The graph of ƒ intersects the x-axis at B and the y-axis at A. P(x; 0) is any point on the interval OB. D lies on f such that CD 1 AO and DP 1OB. (a) Determine the length of OA and OB. (b) Determine the length of OC in terms of x. (c) Prove that the area of quadrilateral OBDA is equal to: A(x)=-x+4x+8. (d) For which value of x is the area of the quadrilateral is a maximum? 3x²+4 =6 22 D (010) P(x;0) B lxb 8-13 8-x³× 4x >​