a) 1f04=(2.5) -(6.2) j+ (1.7 )k, find the directional cosines b) If OB= (1.8)i-(3.7) j+ (9.2 )k, using O4 from part a), find the area of the triangle OAB. Calculate to an accuracy of 3 d.p. (4 marks) (6 marks) c) From its current Cartesian form, convert z = 2.576 - 1.874 j into exponential form (7 marks) d) Using the calculated value of z, as in part c), rotate z clockwise through an angle 57 using z, =68 3r; . Convert the result into Cartesian form