Great solutions, CPhill! Thank you!

Yes, this is an application of Heron's Formula!

Thanks! Very helpful!

Thank you, both CPhill and azsun for wonderful solutions!

Thanks, guys!

Very, very nice, detailed solution, hectictar! Bravo!

Thank you so much, CPhill! Wow, amazing! I understand it much better now!

Thanks so much, CPhill!

A fire!

Thanks, EP! You're amazing!