Solution: A quadrilateral RSTU whose vertices are R(−4, 1) , S(4, −1) , T(3, −6) , and U(−5, −4).
RS = [tex]\sqrt{(4+4)^{2}+(-1-1)^{2}} =\sqrt{64+4}= \sqrt{68}[/tex]
ST= [tex]\sqrt{(4-3)^{2}+(-1+6)^{2}}= \sqrt{1+25} =\sqrt{26}[/tex]
TU=[tex]\sqrt{(3+5)^{2}+(-6+4)^{2}}= \sqrt{64+4}= \sqrt{68}[/tex]
UR =[tex]\sqrt{(-5+4)^{2}+(-4-1)^{2}}= \sqrt{1+25} =\sqrt{26}[/tex]
→RS=TU, and ST=UR⇒ Opposite sides are equal.
Slope of RS = [tex]\frac{-1-1}{4+4} = \frac{-2}{8}= \frac{-1}{4}[/tex]
Slope of TS= [tex]\frac{-6+1}{3-4} =\frac{-5}{-1}=5[/tex]
Slope of RS × Slope of TS = -1/4 × 5 = -5/4 ≠ -1, So lines are not perpendicular.
∴ quadrilateral RSTU is not a rectangle.
