I have 3 sides of an oblique angle. How do I find the degree?

Answer 1

let the lengths of the sides of the TRIangle be a, b, c, and the angles opposite those sides be A, B, and C. Law of cosines, which generalizes the Pythagorean Theorem, tells you:

c² = a² + b² - 2ab cos C, and
b² = a² + c² - 2ac cos B, and
a² = b² + c² - 2bc cos A

So to find, eg., angle A, solve
a² = b² + c² - 2bc cos A
a² - b² - c² = -2bc cos A
(a² - b² - c²) / -2bc = cos A
A = inv cos [(a² - b² - c²) / -2bc]

Answer 2

Do you have the length of each side? Use sin a/a = sin b/b = sin c/c, or a^2 = b^2 + c^2 + 2bc cos a