Write 1-2i in Polar Form - Solve Confusion

[dylanhouse]

Homework Statement

How do I write 1-2i in polar form?

Homework Equations

The Attempt at a Solution

I know r=√5, and when using x=rcosθ, I get angle of 63.43 or 296.57. However, when I take the sin inverse of-2/√5 I get -63.43. I am really confused.

 

[Mark44]

Homework Statement

How do I write 1-2i in polar form?

Homework Equations

The Attempt at a Solution

I know r=√5, and when using x=rcosθ, I get angle of 63.43 or 296.57. However, when I take the sin inverse of-2/√5 I get -63.43. I am really confused.

The angle is in the 4th quadrant, so it would be either -63.43° or +296.57° (assuming your figures are correct.

 

[rude man]

Homework Statement

How do I write 1-2i in polar form?

Homework Equations

The Attempt at a Solution

I know r=√5, and when using x=rcosθ, I get angle of 63.43 or 296.57. However, when I take the sin inverse of-2/√5 I get -63.43. I am really confused.

The formula is arc tan (Im part)/(Real part). You need to keep track of the numerator and denominator signs to make sure you land in the correct quadrant. In other words, the fact that the I am is - and the Re is + tells you which quadrant to land in.