Answer:
Step-by-step explanation:
Use the midpoint formula: 
So, the Change In X is 2-8 = -6
And the Change in Y is 7-4 = 3
Once you divide both of the changes by 2, you get
X: -3
Y: 
So the midpoint is: 
<span>D) perpendicular bisector <em>I believe.
</em></span>
Answer:

Given:
Volume of cube = 140.608 cubic millimetres
Step-by-step explanation:
Let the length of each side of cube = a

Therefore length of each side of cube = 5.2 mm
You can focus on the two sub-triangles ABC and ACD
We know that they are both right triangles, because we're given that AC and BD are perpendicular.
The sides AB and AD are the hypothenuses of these triangles, so we know their length through the pythagorean theorem:


But since we're given
, the expressions for AD and AB are actually the same expression. This proves that AD=AB, and thus that the triangle is isosceles.