The algebraic descriotion is;
R (x,y) = R'(y + 0, 0-x)
The new endpoints of the line BK are B'(4,-1) and K' (-3,-4)
Here, we want to rotate the end points of the line segment at an angle of 270 degrees clockwise about the origin
To rotate a certain point at 270 degrees clockwise about the origin, we have;
R (x,y) to R' (y, -x)
The algebraic description is simply;
R (x,y) = R'(y + 0, 0-x)
To get the new endpoints, we simply write the transformation as shown;
(1,4) becomes (4,-1)
(4,-3) becomes (-3,-4)