You can calculate the area of a triangle if you know the lengths of all three sides, using a formula that has been know for nearly 2000 years.

It is called "Heron's Formula" after Hero of Alexandria (see below)

Step 1: s = (5+5+5)/2 = 7.5 Step 2: A = √(7.5 × 2.5 × 2.5 × 2.5) = √(117.1875) = 10.825...

Try it yourself:

The formula is credited to Hero (or Heron) of Alexandria, who was a Greek Engineer and Mathematician in 10 – 70 AD.

Amongst other things, he developed the Aeolipile, the first known steam engine, but it was treated as a toy!

In the calculator above I have also used a special formula to calculate the angles (to provide a complete solution). The formula is:

Where "C" is the angle opposite side "c".