1. a : ℝ^2
2. b : ℝ^2
3. |a⋅b| < (||a|| * ||b||)
⊢ ((b 0) * (a 1)) - (a 0) * (b 1) ≠ r0
{ (RWO "square-nonzero<" 0 THENA Auto) }
1. a : ℝ^2
2. b : ℝ^2
3. |a⋅b| < (||a|| * ||b||)
⊢ (((b 0) * (a 1)) - (a 0) * (b 1)) * (((b 0) * (a 1)) - (a 0) * (b 1)) ≠ r0