Answer :
length of DE = 3-(-1) = 4
SIDE DE is a vertical line
horizontal distance between E and F is 3 - (-2) = 5
So the area of triangle DEF = 0.5 * 4 * 5 = 10 sq units
SIDE DE is a vertical line
horizontal distance between E and F is 3 - (-2) = 5
So the area of triangle DEF = 0.5 * 4 * 5 = 10 sq units