1)z = r(cos a + isin a)
z = a+bi
r = √a²+b² = √2
cos a = 1/√2
sin a = -1/√2
a = 2π-π/4 = 7π/4
z = √2(cos7π/4 + isin 7π/4)
2)z = r•e^ai
z = √2e^i•7π/4
