1 + cot(x)i , express in modulus argument form where 0 < x < pi/2

I understand how to get the modulus by finding (1 + cot^2(x))^1/2 = cosec(x)

but the answer gives cosec(x)cis(pi/2 - x), i dont understand why the (pi/2 - x) is needed and not just cis(x).