To solve a triangle you find all missing sides and angles.
For a right triangle use
Cos(angle)= adjacent/hypotenuse
Sin(angle)= opposite/hypotenuse
Tan(angle)= opposite/adjacent
Opposite ^2+ adjacent^2= hypotenuse^2
For non right triangles
Law of sines
SinA/a=SinB/b=SinC/c
Law of cosine
a^2= b^2+c^2-2bcCosA
