A robot arm PQ with end coordinates P(0,0) and Q(2,5) rotates

A robot arm PQ with end coordinates P(0,0) and Q(2,5) rotates counter clockwise about P in the XY plane by 90°. The new coordinate pair of the end point Q is

For the new coordinate pair

	x'		=		cosθ		-sinθ			x
	y'				sinθ		cosθ			y

where (x',y') is coordinate at point θ.
by putting θ = 90°

	x'		=		0		-1			x		=		0		-1			2
	y'				1		0			y				1		0			5

	x'		=		-5
	y'				2