# Thread: [SOLVED] How to solve this?

1. ## [SOLVED] How to solve this?

Find the argument of z = -4 + 7i

2. Originally Posted by mark1950
Find the argument of z = -4 + 7i
Imagine your standard 2D graph where the horizontal line is the real axis (Re) and the vertical line is the imaginary axis (Im).

From the origin you can plot the point (-4,7) and it should become apparent how to find the arguement

Spoiler:
$tan(\theta) = \frac{7}{-4}$

this is the angle to the horizontal, if you need the vertical angle then take theta from 90

3. $z = - 4 + 7i\, \Rightarrow \,\arg \left( z \right) = \pi + \arctan \left( {\frac{7}{{ - 4}}} \right)$