Left angle triangle is opposite of right angle triangle which has a rigid structure in the shape of 'L' with one arm fixed to a vertical surface. A right angle is called from the Latin with a line having 90 degrees from the ground and left angle is more looks like an oddity, which it follows from the existence of the right angle. Here, you can refer the below tutorial which explains you on left angle triangle with Pythagoras deconstructed.
Pythagorean Mystery generates a number of epistemological tensions. The left-angled triangle has the effect which have been mitigated: the 'left' indicates with sinister (from the Latin), or 'left over' (unnecessary, prone to be thrown out), or 'left off' (deleted, censored) or most powerfully left alone (isolated, outcast).
0.97c2 < a2 + b2 < l.0l c2