1, the answer is that C is 45 northeast of A, and C is 400 km away from A/kloc-0 ... Let A, B and C be ABC points respectively, and the angle 1 is 15, then the angle ABC is 75- 15 = 60, and the triangle ABC is.

1, not necessarily equal, but equal when the same number is different: the numbers of two different numbers are added to get the number with larger absolute value, and the number with smaller absolute value is subtracted from the number with larger absolute value. Of course, it cannot be equal to the sum of two absolute values.