hero’s formula to the rescue
Both of these dea
Let’s work on the triangle tub next. You need to work
backward from area to find side length. Which tool from
your Geometry Toolbox is the best one for this job?
Hero’s formula is A = s(s-a)(s-b)(s-c).
It finds area in terms of the sides of the
triangle, so it’s a good fit with our problem:
finding perimeter from area.
o do qui
te a lot
o get t
the sides. Not our f
Ringing bells but kind of
heck out page 196
self how t
use Hero’s formula.
N, Z, and
1/2 base x
All your toolbox tools are arranged by
subject in a downloadable PDF at
Working smarter, not harder is often about choosing the
right tool for the job. Go to www.headfirstlabs.com/geometry to
grab yourself a handy printable reference sheet of
your geometry tools grouped by topic.
290 Chapter 7