solve a triangle using sines

beacuse i looked it up and it just counfused me so much more

may be it will help:

https://www.youtube.com/watch?v=Ex2vASCpq2Y

or

http://web2.0calc.com/questions/find-the-number-of-distinct-triangles-with-measurements-of-a-31-a-10-and-b-40

Thank you.