(a) In unit-vector notation, what is the sum of a = (4.3 m )i + (3.7 m ) j and b = (- 12.0 m )i+ (6.9 m )j. What are (b) the magnitude and (c) the direction of a + b (relative to i)? (a) Number it i Units (b) Number i Units (c) Number i Units eTextbook and Media Hint Assistance Used Add the vectors as in Sample Problem 3-4 or using a calculator (rectangular mode). Convert the answer to magnitude-angle (spherical) mode on the calculator or draw the components of the answer in a perpendicular, head-to-tail arrangement. Then use