If you draw the coordinate, it's easy to understand. First, draw a line between (-2,1) and (3,1). This is the base of the triangle, which is the distance between 3 and -2, that's 5.

Now we need to find the height of the triangle. From |y-1|=1, we know that possible values for y is either 2 or 0. Draw two lines, y=2 and y=0 (falls on axis x). These 2 lines are parallel to the first line we drew above. So the distance between them is always 1.

For the last vertex (x,y), it will always fall on those 2 lines. No matter where x is, height of the triangle is always 1.

Area of the triangle is 1/2 x 5 x 1 = 5/2.

Small correction. The base is 5. 3-(-2) = 5.

Oops, you are right Kamu. I fixed it in my posting so nobody will get confused...

Thanks!