Question

Which ordered pair gives the coordinates of the image of R(-a, b) if R is rotated clockwise 180°?

(b, -a)
(a, -b)
(-b, -a)
(a, b)

Answer 1

Rule for a clockwise rotation of 180 is 
$r_{180}(x,y) \rightarrow (-x,-y)$

$r_{180}R(-a,b) \rightarrow R'(a,-b)$

Answer 2

The correct answer is:

(a, -b)

Explanation:

A 180° rotation maps every point (x, y) to (-x, -y).  This means that both the x- and y-coordinates are negated.

For the point R(-a, b), this means that both coordinates are negated; this gives us R'(a, -b).