sin17π/8*cos7π/4-cos7π/8*sin3π/4=sin(2π+π/8)*cos(2π-π/4)-cos(π-π/8)*sin(π-π/4)=sinπ/8*cosπ/4-(-cosπ/8)*sinπ/4=sinπ/8*cosπ/4+cosπ/8*sinπ/4=sin(π/8+π/4)=sin(3π/4)=sin(π-π/4)=sin...