500,000 is that number rounded.
Answer:
The length of the legs is 8.64cm and 14.64cm respectively
Step-by-step explanation:
I've added an attachment to aid my explanation.
At different intervals, I'll be making reference to it.
Given



From the attachment, we have:

Since, M is the Midpoint

Substitute 17 for AB


Also, from the attachment


Substitute 8.5 for y


--------- (1)
Also, from the attachment

Substitute 8.5 for z


----------- (2)
Subtract (2) from (1)


Make x the subject

Apply Pythagoras Theorem:
We have that:

The above can be replaced with
(see attachment)

Substitute 6 + w for x




Reorder

Solve using quadratic equation:

Where







Split:
or 
or 
or 
But length can't be negative
So:

Recall that: 


<em>Hence, the length of the legs is 8.64cm and 14.64cm respectively</em>
Since this is in point-slope form, you know one of the points, which is (1,7), and you know the slope, which is -3. So you can plot (1,7) on the graph and then use the slope to plot more points by going down 3 and right 1, or up 3 and left 1.
In the complex plane, the two given points are represented by

and

. The midpoint would then be

which represents the complex number

.