已知sin(π-α)=3/5,则cos(π+α)=( )
A,4/5 B,-4/5 C,+-4/5 D,+-3/5
sin(π-α)=3/5=sinα
cos(π+α)=-cosα
根据(sinα)^2+(cosα)^2=1 cosα=+-4/5
-cosα=+-4/5
选C