# Math Help - herons formula

1. ## herons formula

round to the nearest square unit using herons formula
a=13 yards b= 9 yards c=5 yards

2. Hello, Shorty!

Exactly where is your difficulty?

You do have the formula and you do have a calculator . . . right?

Heron's Formula: . $A\;=\;\sqrt{s(s-a)(s-b)(s-a)}$

. . where $s$ is the semiperimeter: $(a + b + c)/2$

Round to the nearest square unit using Heron's Formula:
. . a = 13 yards, b = 9 yards, c = 5 yards

$s\;=\;(13 + 9 + 5)/2 \;= \;13.5$

$A \;= \;\sqrt{((13.5)(13.5-13)(13.5-9)(13.5-5)} \;= \;\sqrt{(13.5)(0.5)(4.5)(8.5)}$

. . $= \;\sqrt{258.1875} \;= \;16.0821396\;\approx\;16\text{ yd}^2$