1. square difference formula: $ (a+b) 2 = a 2+2ab+b 2, (a-b) 2 = a 2-2ab+b 2 $2. Cubic difference formula: $ A 3+B 3 = (A 3-B 3 = (A-B) (A 2+AB+B 2) $3. Complete square formula: $ a 2-b 2 = (a+b) (a-b) $4. Binomial Theorem: $ (a+b). 1'= 60'',1= 3600'' $6. Sine theorem: $ \ \ frac {a} {\ \ Sina} = \ \ frac {b} {\ \ sinb} = \ \ frac} Because eight dollars. Pythagorean theorem: $ a 2+b 2 = c 2 $9. Similar triangles's proportional formula: $ \ \ frac {a} {a'} = \ \ frac {b} {b'} = \ \ frac {c} {c'}