if the sides of the triangle are given by 20 cm, 30 cm, and 60 cm find the area of the triangle.
I tried a long time. Apparently, Heron's formula does not seem to work
where $s = (a+b+c)/2$
In the above problem $s=55$ and thus we end up with a negative number inside square root. I am not sure if there is any other formula to be applied to this problem .