如果做錯請告訴我.
原式= (1+cos^2x-sin^2x)/2cosx + sinx +a^2 * sin(x+π/4)
=(sin^2x+cos^2x+cos^2x-sin^2x)/2cosx +sinx +a^2 * sin(x+π/4)
=2cos^2x/2cosx +sinx +a^2 * sin(x+π/4)
=cosx+sinx+a^2 * sin(x+π/4)
=√2 sin(x+π/4)+ a^2 * sin(x+π/4) (這一步是合一變型)
=(√2+ a^2 )* sin(x+π/4)
因?yàn)閟in(x+π/4) Max=1
所以(√2 + a^2 ) =√2+3
所以. 接下來自己做咯``
打得好累.