1. Use de Moivre's formula to prove the double angle formulas: cos(26) = cos2 +9 | sin]2 6' (1) sin[26') 2 sin 9 cos .9 (2) 2. Use the polar representation of complex numbers to prove the trigonometric addition formulas: cos(6' qb) = cos .9 cos gt) sin 6' sin ti) (3) sin(6' 4b) = sin 9 cos (3') + cos 6' sin ti) (4) 3. Use the polar representation of complex numbers to prove the trigonometric subtraction formulas: cos(6' qb) = cosBcosgti | sin'singb (5) sin(6' 4b) = sin cos (3') cos' singb (G)