Is the figure a rectangle? explain.

Here is the first sign that should tell you this isn't a rectangle. 

d=_/w^2+l^2 is the equation to solve the diagonal of a rectangle

if you plug in 21 and 20, d would equal 29 not 28 so for that reason alone it is not a rectangle.

I am about 90% sure the correct answer is B. I hope this helps let me know if I was right.

Option B!

The slope of the function is 0.5.