® Area of a triangle with vertices (x1, y1), (x2, y2) and (x3, y3) is given by
1
1
2
2
3
3
1
1
1
2
1
x
y
x
y
x
y
∆=
® Minor of an element aij of the determinant of matrix A is the determinant
obtained by deleting ith row and jth column and denoted by Mij ® Cofactor of aij of given by Aij = (– 1)i+ j Mij
® Value of determinant of a matrix A is obtained by sum of product of elements
of a row (or a column) with corresponding cofactors For example,
A = a11 A11 + a12 A12 + a13 A13 ® If elements of one row (or column) are multiplied with cofactors of elements
of any other row (or column), then their sum is zero