c)[tex]BD= \sqrt{(X {B-XD)^{2} \left +(YB-YD)^{2}
[/tex]
[tex]BD= \sqrt{(-5-3) ^{2}+(1-1)^{2} [/tex]
[tex]BD= \sqrt{64}
[/tex]
[tex]BD=8
[/tex]
[tex]AC= \sqrt{(XA-XC)^{2}+(YA-YC)^{2} [/tex]
[tex]AC= \sqrt{(-1+2)^{2} +(4+1)^{2} [/tex]
[tex]AC= \sqrt{1 ^{2}+5^{2}
[/tex]
[tex]AC= \sqrt{26} [/tex]
d)Aria=d₁d₂/2=8√26/2=4√26
