Question

Triangle ABC is defined by the points A(-2,1), B(1,3), and C(5,-1). The area of triangle ABC, rounded to the nearest hundredth, is ____ square units.

Answer 1

10.00 square units

Explanation:

The area can be computed directly from the coordinates using the formula ...

Area = (1/2)|Ax(By -Cy) +Bx(Cy -Ay) +Cx(Ay -By)|

= (1/2)|-2(3-(-1)) +1(-1-1) +5(1-3)| = (1/2)|-8 -2 -10| = (1/2)|-20| = 20/2

Area = 10 . . . . square units