Thread: How to find the altitude (height) of a triangle

Please help me, I am completely baffled. I need the formula to find the altitude/height of a triangle (in order to calculate the area, b*h/2) based on the lengths of the three sides. Please, someone help me... I really need it. I searched google and couldn't find anything.

Use the rule of sines for area:



where A is area

Originally Posted by ineedhelp87

Please help me, I am completely baffled. I need the formula to find the altitude/height of a triangle (in order to calculate the area, b*h/2) based on the lengths of the three sides. Please, someone help me... I really need it. I searched google and couldn't find anything.

If you know the lenghts of the three sides, the area follows from Heron's formula.

I have to admit, I didn't really understand the rule of sines... I think I understand Heron's formula though. So does that mean that a triangle with side lengths of 12, 15, and 7 would have an area of 41.231...?

Thank you so much for your help. Sorry to be a mouse with a cookie but if someone could tell me if the answer I got is right so I can make sure I understood everything I would really appreciate it!

Originally Posted by ineedhelp87

I have to admit, I didn't really understand the rule of sines... I think I understand Heron's formula though. So does that mean that a triangle with side lengths of 12, 15, and 7 would have an area of 41.231...?

Yes that is correct.

Originally Posted by Plato

Yes that is correct.

Okay, thank you!!