Can someone help me here?
"The product of 4(cos30 + i sin30) and 3(cos90 + i sin90) is equal to..."
The answer is 6(-1 + i rad(3)) apparently but I don't know where that came from.
I can never remember how to do these for some reason...
That is surely the hard way! The whole point of the "polar form", (also written and even ), is that
Here, (4 cis(30))(3 cis(90))= (12) cis(120)= 12(cos(120)+ i sin(120)). Since the numbers were given in "cis" form, I would leave the answer in that form. If you like, and so