Answer:
Because sin 0 and csc 0 establish a relationship where one is reciprocated to the other.
Explanation:
Sin 0 is found according to the mathematical expression Sin 0 = y / r.
The csc 0, in turn, is found through the mathematical expression Csc 0 = 1 / sin 0, which is equivalent to y / r.
In both expressions the letter "r" will always be represented by a positive value. This makes Csc 0 and sin 0 have a strong reciprocity and assume the same sign, regardless of the number that represents the "Y". This is because if "y" has a positive value, both sin 0 and csc 0 will have a positive sign, if "Y" will take a negative value, both sin 0 and csc 0 will take negative signs.