6.4.1 sum and difference formulas 6.4.2 sum and difference formulas 6.4.3 sum and difference formulas 6.5.1 double angle formulas 6.4.3 sum and difference formulas 6.4.2 sum and difference formulas 6.4.1 sum and difference formulas 6.5.2 half angle formulas 4.9.1 quad inequal graph 2 var 4.9.3 quad inequal algebraically 4.9.3 quad inequal algebraically 4.9.2 quad inequal tables and line graphs 6.4.3 sum and difference formulas 6.4.2 sum and difference formulas 6.4.1 sum and difference formulas 
