find the missing endpoint if s is the midpoint of rt r(-9,4) and s(2,-1) ; find T

Answer:  The required co-ordinates of point T are (13, -6).Step-by-step explanation:  given that S is the midpoint of the line segment RT, where the co-ordinates of point R are (-9, 4) and that of S are (2, -1).We are to find the co-ordinates of point T.We know thatthe co-ordinates of the mid-point of a line segment with endpoints (a, b) and (c, d) are given by[tex]\left(\dfrac{a+c}{2},\dfrac{b+d}{2}\right).[/tex]Let (h, k) be the co-ordinates of point T. Then, according to the given information, we have[tex]\left(\dfrac{-9+h}{2},\dfrac{4+k}{2}\right)=(2,-1)\\\\\\\Rightarrow \dfrac{-9+h}{2}=2\\\\\Rightarrow -9+h=4\\\\\Rightarrow h=4+9\\\\\Rightarrow h=13[/tex]and[tex]\dfrac{4+k}{2}=-1\\\\\Rightarrow 4+k=-2\\\\\Rightarrow k=-2-4\\\\\Rightarrow k=-6.[/tex]Thus, the required co-ordinates of point T are (13, -6).