1. Section 8.4 Area of a Triangle

7. Note: s is the “semi-perimeter.”

9. Proof of Heron’s Formula Note: Since Heron of Alexandria didn’t have the advantage of trigonometry, this is NOT the proof he gave. C B A a b c

10. Proof of Heron’s Formula Note: Since Heron of Alexandria didn’t have the advantage of trigonometry, this is NOT the proof he gave. C B A a b c

11. Proof of Heron’s Formula Note: Since Heron of Alexandria didn’t have the advantage of trigonometry, this is NOT the proof he gave. C B A a b c In a very similar manner, we can prove that