#### Answer

$\color{blue}{s\approx 8800\text{ km}}$

#### Work Step by Step

Since they are in opposite directions from the equator, the central angle between the two cities is:
$=45^o+34^o=79o$
Convert the angle to radians by multiplying $\dfrac{\pi}{180^o}$ to the angle measure to obtain:
$=79 \cdot \dfrac{\pi}{180^o}=\dfrac{79\pi}{180}$
RECALL:
The length of the arc $(s)$ intercepted by the central angle $\theta$ in a circle of radius $r$ is given by the formula:
$s = r\theta$, where $\theta$ is in radian measure.
Use the formula above to obtain:
$s=r\theta
\\s=6400 \cdot \frac{79\pi}{180}
\\s=8824.384698
\\\color{blue}{s\approx 8800\text{ km}}$