Answer:
I don't know but I have the equations. (also Im going to assume you know a bit of trig)
Step-by-step explanation:
You have to use law of cosines.
a=11
b=15
take these equations and plug in the variables
a^2=b^2+c^2-2bc cos(a)
b^2=a^2+c^2-2ac cos (b)
c^2=a^2+b^2-2ab cos(c)
you will get something along the lines of
something=cos a
something=cos b
something=cos c
then in a calculator you push inverse cos or cos-1(x) and input the "something" into as x and that answer should be one angle, and repeat it for the rest of the three values.