104.5 degree triangle w/ 2 equal legs, need the 3rd leg's length

[CocoonOHorror]

Homework Statement

i have a triangle with 2 legs of 96 inches. the angle between them is 104.5 degrees. how do i get the length of the 3rd leg?

Homework Equations

wish i knew.

The Attempt at a Solution

tried Cos, Sin, and Tan of 104.5 * length of a leg

 

[willem2]

How about the cosine rule?

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

works for unequal legs as well.

 

[DaveC426913]

Draw a line down the centre. Now you have two right-angled triangles. It should be a piece of cake from there.

 

[CocoonOHorror]

How about the cosine rule?

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

works for unequal legs as well.

when i tried this i got 1.17545571, but the answer should be 1.5.

C^2=(.96)^2+(.96)^2-2(.96)(.96)(-.25038)

 

[CocoonOHorror]

Draw a line down the centre. Now you have two right-angled triangles. It should be a piece of cake from there.

thanks man! i think this worked, and i kind of understand why.

i still don't understand why the law of cosines didnt work for me, i wonder what i screwed up...

 

[willem2]

when i tried this i got 1.17545571, but the answer should be 1.5.

C^2=(.96)^2+(.96)^2-2(.96)(.96)(-.25038)

you forgot one of the minus signs in -2(.96)(.96)(-.25038)