What is the difference between law of cosines and the Pythagorean theorem?

1) pythagorean theorem is applicable only for right angled triangles.

2) law of cosines is applicable for all the triangles.

law of cosines : c² = a² + b² − 2ab cos θ

a,b,c are sides of any triangle and θ is angle between a,b

pythagorean theorem :

c² = a² + b².

in a right angled triangle , where c is hypotenuse(side opposite to 90 degrees ) and a,b are other sides.

You could get the Pythagorean theorem from the law of cosines. In the Pythagorean theorem, one angle of the triangle has to be 90 degrees but the law of cosines can be applied to any triangle.

In trigonometry, the law of cosines (also known as the cosine formula or cosine rule) relates the lengths of the sides of a plane triangle to the cosine of one of its angles...//

the Pythagorean theorem or Pythagoras' theorem is a relation in Euclidean geometry among the three sides of a right triangle (right-angled triangle)..//