sin²（π+α）-cos（π+α）cos（-α）+1的值为

原式=1/2*{1-cos[2*(π+α)]}-(-cosα)cosα+1
=1/2-1/2*cos(2π+2α)+cos^2 α+1
=3/2-1/2*cos2α+(1+cos2α)/2
=3/2-1/2*cos2α+1/2+1/2*cos2α
=4/2=2