#### burgerandcheese

##### Junior Member

- Joined
- Jul 2, 2018

- Messages
- 73

If z has modulus 1 and argument θ, where 0 < θ < π, find the modulus and argument of (z - 1)/(z + 1)

I wanna know why the argument of (z + 1)/(z - 1) is "

This came after learning the rules for multiplication and division in modulus-argument form

|st| = |s||t|, arg(st) = arg s + arg t + k(2π),

|s/t| = |s|/|t|, arg(s/t) = arg s - arg t + k(2π)

I wanna know why the argument of (z + 1)/(z - 1) is "

**the angle you have to turn through to get from vector AP to vector BP, that is π/2 anticlockwise, or +π/2**" What does that mean? Does it mean moving AP until it reaches BP? But isn't it always touching BP?This came after learning the rules for multiplication and division in modulus-argument form

|st| = |s||t|, arg(st) = arg s + arg t + k(2π),

|s/t| = |s|/|t|, arg(s/t) = arg s - arg t + k(2π)

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