How do you find the area of a triangle?

  it depends on what data you start with

Step-by-step explanation:

The usual formula for the area of a triangle is ...

  A = (1/2)bh

where b represents the base length of the triangle, and h represents the altitude to that base (the height).

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If you are given two side lengths, a and b, and the angle C between them, the area can be found using the formula ...

  A = (1/2)ab·sin(C)

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If you are given the three side lengths, a, b, c, then the area can be found using Heron's formula:

  A = √(s(s -a)(s -b)(s -c))

where s is the semi-perimeter: s = (a+b+c)/2.

incomplete question. how do you expect anyone to you when you do not post the question in its entirety?