page 06 MARKS 9. (a) Express cos sin 7 ° 3 ° x x  in the form   sin ° k x a  where 0 k , 0 360 a   . (b) Hence, or otherwise, find: (i) the maximum value of cos sin 14 ° 6 ° x x  (ii) the value of x for which it occurs where 0 360 x   . 10. Determine the range of values of x for which the function  3 2 2 9 24 6 f x x x x     is strictly decreasing. 11. Circle C1 has equation     2 2 4 2 37 x y     . Circle C2 has equation 2 2 2 6 7 0 x y x y     . (a) Calculate the distance between the centres of C1 and C2. (b) Hence, show that C1 and C2 intersect at two distinct points. 4 1 2 4 3 3