fact: Definition incircle2d x1 y1 x2 y2 x3 y3 x4 y4 := let X1 := sub x1 x4 in let X2 := sub x2 x4 in let X3 := sub x3 x4 in let Y1 := sub y1 y4 in let Y2 := sub y2 y4 in let Y3 := sub y3 y4 in let Z1 := add (mul X1 X1) (mul Y1 Y1) in let Z2 := add (mul X2 X2) (mul Y2 Y2) in let Z3 := add (mul X3 X3) (mul Y3 Y3) in add (add (mul (sub (mul X1 Y2) (mul X2 Y1)) Z3) (mul (sub (mul X2 Y3) (mul X3 Y2)) Z1)) (mul (sub (mul X3 Y1) (mul X1 Y3)) Z2).
imports: Reals Psatz Flocq(Core Operations Relative Plus_error)