In geometry, Heron's formula (or Hero's formula) gives the area of a triangle in terms of the three side lengths. If ${\textstyle s={\tfrac {1}{2}}(a+b+c)}$ is the semiperimeter of the triangle, the area is,

$A={\sqrt {s(s-a)(s-b)(s-c)}}.$

a:

b:

c:

area:

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