Question

What is the area of a triangle whose vertices are J(−2, 1) , K(4, 3) , and L(−2, −5) ?

Answer 1

Vertices of the triangle: 
J (-2,1), K (4,3), and L (-2,-5) 
Area of triangle: 18

or 
determinant= 
4,3,1 
-2,1,1 
-2,-5,1 
determinant= 4(1+5)-3(-2+2)+1(10+2) = 36 
A = determinant/2
36/2=18 
Notice that one side is vertical. Use that side as base. 
Area is 18.