when you are starting, is your first 1-2 steps supposed to be out in front of you, or should they instead be behind your hips?
in other words, what is close to the optimal angle for your leg to make with the ground in your first step? should it be perpendicular or at 45 degrees, i’ve heard both. how about good angles for your second step? third?
not saying there isnt but,
the only optimal angles i know are one in the start blocks and two the non-existant angles ie, a straight line happening from head to toe as you exit the blocks and three, that your leaning forward somewhat - steeper the angle of the body lean with full straightness from head to toe in drive = faster times. 
The actual angle is dependent on your strength levels. Stronger/more powerful athletes can sustain more of an angle coming out of the blocks.
Make sure that you set up with your feet behind your hips in the blocks and then let it hapen naturally.
Some good drills for getting the feel for the right start angles include lying starts, pushup starts and incline (hill) starts.
