Find the area of the triangle ABC when three sides are a=9,b=12 and c=5?

Answer 1

Area of a triangle = Sqrt (s(s-a)(s-b)(s-c)

where s = (a + b + c)/2

here s = 26/2 = 13

=> area = sqrt(13(13-9)(13-12)(13-5))
= sqrt 416
= 20.4

Answer 2

To find the area of a triangle, multiply the base by the height, and then divide by 2. The division by 2 comes from the fact that a parallelogram can be divided into 2 triangles. For example, in the diagram to the left, the area of each triangle is equal to one-half the area of the parallelogram.

From here: http://www.mathgoodies.com/lessons/vol1/area_triangle.html