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
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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