dharan wrote:

The area of triangle when 3 vertices are given by

= 1/2 [ x1(y2-y3) + x2(y3-y1) + x3(y1-y2)]

x1,y1 = L(1,3 )

x2,y2 = M(5,1)

x3,y3 = N(3,5)

Substituting the 3 values in the formula we get

=> 1/2 [ 1 ( 1 -5 ) + 5( 5 - 3 ) + 3 ( 3 - 1 )]

= 1/2 [ -4 + 10 + 6 ] = 12/2 = 6

the tricky here is to remembering the correct sequence of the formula.

my short cut to remember this formula is to do a circular rotate first three vertices ( x1,y2,y3) by 1 to get second one ( x2,y3,y1) and do the rotate again to get the third one ( x3,y1,y2). OR you can form a 3x3 matrix to remember well.

1/2 [1,2,3 + 2,3,1 + 3,1,2].

Not sure if this is the wise approach but I could solve faster.

I know its a bit random but does this formula have a name?