1. The problem statement, all variables and given/known data Find the modulus and argument of 1) cos(i) 2) -3i 2. Relevant equations 3. The attempt at a solution 1) So for question 1 i tried cos(i) = ½(ei2 + e-i2) = ½(e-1 + e) . However this doesn't (as far as I can see!) lead me to the right answer. I was aiming to get it in the form reix where r is the modulus and x the argument. for 2) I basically just drew an argand diagram and found the radius to be 3 and the argument 3/4pi. if you could point me in the right direction with 1 especially that would be greatly appreciated!