Question

How do I apply Heron's formula for a triangle?
Let's suppose I have a triangle as follows,
and I want to find Cos B ... how would it be?

Answer 1

draw a perpendicular from C on AB

Answer 2

ok .. let's suppose I did it. Now ... :) ?

Answer 3

partition is as x and c-x ,, for c

Answer 4

and put y for that vetical dist

Answer 5

... can you make a sketch please, I can't do it , O_O. too confused !

Answer 6

That's not heron's formula...

Answer 7

That's the law of cosines.

Answer 8

Hmmm... I think that's cosine law in your diagram... Heron's formula is used to find the area of triangle :S

Answer 9

ok whatever, tell me how do I find cos B if I have all sides given ? :(

Answer 10

Heron's formula gives the area of a triangle given three side lengths

Answer 11

http://en.wikipedia.org/wiki/Heron%27s_formula

Answer 12

http://en.wikipedia.org/wiki/Law_of_cosines

Answer 13

Put the values into the formula :S

Answer 14

Plug in the values, then take the arccosine

Answer 15

or cos^(-1)

Answer 16

Should be on your calculator.

Answer 17

i was thinking the same ... thought i couldn't remember the exact proof. except vector dot product.

Answer 18

... ok hold on a second I have something.. to show !

Answer 19

Give the three side lengths, and we'll walk you through. NOte that this is the law of cosines.

Answer 20

... ok , I had this problem time ago , and I did it. (at least I thought I did it.) the area I got was 72. but tell me formulas which are to find area of this triangle ans Cos B

Answer 21

for triangle ABC

Answer 22

tell me angle, and for all triangle how do you find area , if you don't mind :(

Answer 23

okay ... i figured it out.