Given a triangle with sides $$a, b$$ and $$c$$ Heron's formula is:
$$A=\sqrt{p \cdot (p-a) \cdot (p-b) \cdot (p-c)} $$
where $$p$$ is the semiperimeter:
$$p= \dfrac{a+b+c}{2}$$
It works when all the sides of a triangle are known we can calculate the area with no need to know the height.