DeMoivre s Theorem For a complex number in polar form r cos i sin r cos no i sinne Question Calculate 3 cos 60 i sin 60 NOTE You will have to submit your scratchwork for these problems in the next question for full credit For more information on this topic look in your textbook at section 6 5 You might also want to look at the Complex Numbers presentation 81 cos 240 i sin 240 12 cos 240 i sin 240 81 cos 60 i sin 60