Formula: 1 Mark
Steps: 2 Marks
Answer: 1 Mark
Let the third vertex be (x, y)
Using mid-point formula, we have
x+52=0⇒x=−5
and y+22=3⇒y=4
or
x−12=0⇒x=1,
y+42=3⇒y=2
(0,3) can be the midpoint of either side. So we are getting two values of the vertex of the third side.
Hence, third vertex is (-5, 4) or (1,2)