math question - length of a side of a triangle

[sarie]

Hi all,

I worked through the flashcard questions for college math, and thought I did fairly well. However, when I got to the clep practice test, I ran into some difficulties. I was able to get them all sorted out except for this one:

In triangle ABC shown above, what is the length of the segment AB?

I'll have to describe the picture to you, because I can't paste it.

It's an obtuse triangle. Angle C is 120 degrees. BC is given as 6, and AC is given as 10. How do you figure out the length of AB, since ABC is not a right triangle?

Any help would be appreciated!

[brothert69]

Hi all,

I worked through the flashcard questions for college math, and thought I did fairly well. However, when I got to the clep practice test, I ran into some difficulties. I was able to get them all sorted out except for this one:

In triangle ABC shown above, what is the length of the segment AB?

I'll have to describe the picture to you, because I can't paste it.

It's an obtuse triangle. Angle C is 120 degrees. BC is given as 6, and AC is given as 10. How do you figure out the length of AB, since ABC is not a right triangle?

Any help would be appreciated!

Law of Cosines
Law of cosines - Wikipedia, the free encyclopedia

For this case

AB= sqrt(BC^2+AC^2-(2*BC*AC*cos©))

AB=sqrt(36+100-(2*6*10*-0.5))

AB=sqrt(36+100-(-60))

AB=sqrt(196)

AB=14

[LaterBloomer]

English, please.

[cookderosa]

English, please.

Look this up on Khan Academy, he's good at translating mathish into English.

[brothert69]

Look this up on Khan Academy, he's good at translating mathish into English.

Totally forgot about Khan Academy.