Is that formula proper isn't it 1/2[x1(y2-y3) x2(y3-y1) x3(y1-y2)]So I

This question was asked in Ex 10.1, 1

Is that formula proper isn't it 1/2[x1(y2-y3) x2(y3-y1) x3(y1-y2)]
So I think solution may change . In this question they have taken formula as 1/2[x1(y2-y3) x2(y3-y1) x3(y1-y3)]