Tom K. answered 10/31/20
Knowledgeable and Friendly Math and Statistics Tutor
The range is rule-driven.
For the domain, we just consider the range of the inverse of the function
a) Domain is the range of cos(x), [-1, 1]
Range is [0, π]
b) Domain is the range of sin(x), [-1, 1]
Range is [-π/2, -π/2]
c) Domain is the range of tan(x), (-∞, ∞)
Range is (-π/2, -π/2)
Note how the endpoints are not part of the range, because tan is not defined there.