
The equation of a elipse:

The length of the major axis is equal 2a if a > b or 2b if b > a.
We have

therefore the length of the major axis is equal 2 · 7 = 14.
Does this help? If it doesn't i can try to explain more if you want.
That is all the work needed to solve this problem
the circle is 5; the triangle is 2; and the square is 6