let
A(2,5)
B(13,11)
C(13,5)
using a graph tool
see the attached figure
area of triangle=AC*BC/2
distance AC
d=√[(y2-y1)²+(x2-x1)²-----> d=√[(5-5)²+(13-2)²---> d=√[11²]
dAC=11 units
distance BC
d=√[(y2-y1)²+(x2-x1)²-----> d=√[(5-11)²+(13-13)²---> d=√[-6²]
dBC=√36 units-----> dBC=6 units
area of triangle=AB*BC/2-----> 11*6/2----> 33 units²
the answer is
33 units²
