D, as a frame goes around the entire photo, so having the perimeter would show the length of wood needed to surround the photo.
I think that it is geometry.
Answer:

Step-by-step explanation:
Given : Vertices of Triangle
,
and 
To find : Centroid of a triangle
The centroid of a triangle is the point of intersection of the three medians of the triangle.
The formula to calculate the centroid of a triangle is:

Where,
are the coordinates of the centroid
Substituting the values in the formula gives us:



Therefore, 
Answer:
16.33628179866692
Step-by-step explanation:
I dont know how far you wanted me to round so you will have to do that part
Answer:
C
Step-by-step explanation:
because yeah