I am leaning pre-cal right now and I don't understand it. I did arctan (3/-5) but got it wrong, how do you do this?

9514 1404 393

  149.04°

Step-by-step explanation:

You must consider the signs of the components of the vector. The value -5+3i will be in the 2nd quadrant of the complex plane.

When you use the single-argument arctan function, it will tell you the angle is -30.96°, a 4th-quadrant angle. (arctan( ) is only capable of giving you 1st- or 4th-quadrant angles.)

You find the 2nd-quadrant angle by adding 180° to this value:

  -30.96° +180° = 149.04° = arg(-5+3i)

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The attachments show the calculation using a suitable calculator (1st) and a spreadsheet (2nd). The spreadsheet function ATAN2(x,y) gives the 4-quadrant angle in radians, considering the signs of the two arguments. Here, we converted it to degrees. The calculator can be set to either degrees or radians.

incomplete question. how do you expect anyone to you when you do not post the question in its entirety?

d

gimmee one of those gold crowns!

~coco