1、y=(cos²x+sin²x)(cos²x-sin²)+1=cos²x-sin²x+1=cos2x+1===2cos²x-1+1=2cos²x.
2、y=(5/4)sin2x-(5/2)cos²x+6=(5/4)sin2x-(5/4)[cos2x+1]+6=(5/4)[sin2x-cos2x]+(19/4)
=[(5√2)/4]sin(2x-π/4)+(19/4)
1、y=(cos²x+sin²x)(cos²x-sin²)+1=cos²x-sin²x+1=cos2x+1===2cos²x-1+1=2cos²x.
2、y=(5/4)sin2x-(5/2)cos²x+6=(5/4)sin2x-(5/4)[cos2x+1]+6=(5/4)[sin2x-cos2x]+(19/4)
=[(5√2)/4]sin(2x-π/4)+(19/4)