Question

已知f(x)=(2sinθcosθ+5/2)/sinθ+cosθ

Answer 1

f(x)=(2sinxcosx+5/2)/sinx+cosx

=3cosx+5/(2sinx)

π/12=15(省略度)

cos(15)=cos(45-30)=cos45cos30+sin45sin30=√6/4+√2/4

sin(15)=(√6-√2)/4

1/sin(15)=√6+√2

f(π/12)=3(√6+√2)/4+10(√6+√2)/4=13(√6+√2)/4

f(x+1)=3cos(x+1)+5/[2sin(x+1)]