Question

Pragati seth area of triangle is 19 square units whose vertices are 3 - 4 - 1, 3 and 5 to do you agree with pragati justify your answer

Answer 1

If (x1, y1), (x2, y2) and (x3, y3) are the vertices of a triangle then its area is given by 1 2 [x1(y2 - y3) + x2( y3 - y1)+ x3(y1 - y2)] square units. Given the vertices of a triangle are (1,-3),(4,k) and (-9,7) and its area is 15 sq .units. ⇒ 15 = 1 2 [1(k - 7) + 4( 7 + 3) + (-9)(-3 - k)] 30 = k - 7 + 40 + 27 + 9k 10k + 60 = 30 10k = -30 ∴ k = -3.