The area of an ellipse with axes of length 2a and 2b is ab.
The percent change in the area when a increases by
2.74% and b increases by 2.65% is

The area increases by 5.46261%

Step-by-step explanation:

Well firstly, the area of an ellipse is not ab, but it's proportional to ab ( where a and b are the semi-minor and semi-major axes).

This tells us that when a increases by 2.74% and b increases by 2.65% the new area will be:

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.