4. Complex numbers: Use MATLAB to compute the following. 5+4i 3 3 (a) (3+61)(-7-91), -1, and Can you check the result by hand 5-41' 2 2i calculations? (b) e. Check the Euler's formula em = cos x+isin x by computing the right hand sides too, i.e., compute cos(7/4)+ i sin(1/4). (c) Execute the commands exp(pi/2*i) and exp (pi/2i). Can you explain the difference between the two results