The area of a triangle is 5 sq. units. Two of its vertices are at (2, 1) and (3, -2). If third vertex is (72,y), find y.
Area of triangle = 12|x1(y2−y3)+x2(y3−y1)+x3(y1−y2)|=5
⇒|2(−2−y)+3(y−1)+72(1+2)|=10
⇒|−4−2y+3y−3+212|=10
⇒y+72=10 or y+72=−10
∴y=132 or y=−272