ABC is a triangle with sides a,b and c. show that :

if then A=2B

I try to use the cosine law, but no result

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- Dec 15th 2010, 07:41 AMrazemsoft21Show that ....
ABC is a triangle with sides a,b and c. show that :

if then A=2B

I try to use the cosine law, but no result - Dec 15th 2010, 06:37 PMtonio
- Dec 16th 2010, 05:09 AMSoroban
Hello, razemsoft21!

Quote:

We are given: .

Law of Cosines:

.[1]

. . . . . .

. . . . . .

. . . . . . .[2]

Since [1] = [2], we have: .

. . Therefore: .

- Dec 16th 2010, 05:27 AMrazemsoft21
- Dec 16th 2010, 06:12 AMtonio
- Dec 18th 2010, 04:36 PMArchie Meade
- Dec 19th 2010, 02:51 PMrazemsoft21