Name: Allan
Who is asking: Teacher
Question: sin 2x = cos 3x Primary question: how do you handle the cos 3x? Hi Allan, You can use the multiple angle expressions for sin(x+y) and cos(x+y) to write cos(3x) in terms of cos(x) and sin(x). = cos(2x)cos(x)  sin(2x)sin(x) = [1  2sin^{2}(x)]cos(x)  2sin(x)cos(x)sin(x) = cos(x)  2sin^{2}(x)cos(x)  2sin^{2}(x)cos(x) = cos(x)  4sin^{2}(x)cos(x) Also Equating the expressions for cos(3x) and sin(2x) you can extract a factor of cos(x) and be left with a quadratic in sin(x) that can be solved using the general quadratic. Paul and Chris
