In order to determine the are of the given triangle, you first calculate the distance between vertex of the triangle. You use the following formula for the distance betwen two points of coordinates (x1,y1) and (x2,y2):
d = √((x2 - x1)² + (y2 - y1)²)
distance between (-2,-4) and (2,-4):
d1 = √((2 - (-2))²+(-4-(-4))) = √16 = 4
distance betwee (2,-4) and (2,5):
d2 = √((2-2)+(5-(-4))) = √1 = 3
each of the prvious distances represent a side of the right triangle. The area is calculated by using the following formula:
A = d1 x d2)/2