Unsure as to why answer is negative

[KrabLord]

If angle A = 20° and line AB = 5, then line BC = ?

The problem, at the bottom of the photo, and the relevant triangle are included in a photo I’ve attached:

The answer I found is ~1.71, but the paper (MIT trigonometry 2011 study guide) says the result is about -1.71. Why is the answer negative?

 

[Dr.Peterson]

You probably misread the answer. It's a length; how can it be negative?

Can you show an image of what it says?

 

[Jagulba]

Could it be just a miss print... the sign - and ~ can look alike sometimes if you are not paying attention

 

[KrabLord]

You probably misread the answer. It's a length; how can it be negative?

Can you show an image of what it says?

 

[Jagulba]

5*sin20
5 is positive,sin20 is positive, how can the multiplication be negative ?
dont read too much into it, its a misprint