My Mortal Enemy

The mortal enemy lurks behind my back,
Always ready to attack,
It shoots red 'F's onto my tests,
I try to dodge them, I give it my best,
But it sticks right onto my paper shield,
And good results I cannot yield.
I've lost the war, it's made its mark,
For math has left me in the dark.
Just when I thought trigonometry would come to my surface area,
And protect me from algebra ,
It turned it's face on me and took the rule of Pythagoras.
I made a friend, she's really sweet, her name is Indices,
But she burned up my paper shield, so full of surprises.
The volume of hate for my mortal enemy,
Cannot be square rooted for the hate is firmly rooted,
In the perimeter of my mind.
Pii left a bit of a mess for me to clean up,
In buckets of water I see my reflections,
My mind views them from a different angle,
Rotating them at 90 degrees.
My mortal enemy is never pleased.
90 percent of me wants to give up,
And the ratio of hate to love has left me in the shadows.
Which axis do I cut, how do I connect the dots?
A graph of my life has left me with no path.
Counting numbers is just like counting sheep,
So it's not my fault if I do fall asleep,
In the presence of you, my mortal enemy.
Length and width should give you my B.M.I,
You're the center of my troubles, I can't deny,
When will I get over you, my mortal enemy?
When will I be done with you, when will we be through?