He is incorrect because each number is in a different place and those different places are worth more or less than the other places
Answer:
Don't quote me on this, but I think that the answer is C.
Answer:
Use Heron's formula; see below.
Step-by-step explanation:
Use Heron's formula.
Let the sides of the triangle have lengths a, b, and c.


Example:
A triangle has side lengths 3, 4, and 5 units.
Find the area of the triangle.







