Question

求sinx＋cosx的值？

Answer 1

sinx＋cosx
=√2(√2/2×sinx+√2/2×cosx)
=√2(sinxcos45°+cosxsin45°)
=√2sin(x+45°)

也可表示为

sinx＋cosx
=√2(√2/2×sinx+√2/2×cosx)
=√2(sinxsin45°+cosxcos45°)
=√2cos(x-45°)

Answer 2

sinx＋cosx
=√2(√2/2sinx+√2/2cosx)
=√2(sinxcos45+cosxsin45)
=√2sin(x+45)