Norton's theorem

例句：

1. 1.The Norton's theorem states that the sum of the angles in a triangle is always 180 degrees.
   诺顿定理表明，三角形内角之和总是180度。
2. 2. In mathematics, the Norton's theorem is used to prove the existence of complex numbers.
   在数学中，诺顿定理被用来证明复数的存在。
3. 3.The Norton's theorem has been proven to be true for all non-zero real numbers.
   诺顿定理对所有非零实数都已被证明是正确的。