CK-12 Foundation
Ck 12: Trigonometry: Inverses of Trigonometric Functions
[Free Registration/Login may be required to access all resource tools.] Here you'll learn how to find the domain and range of inverse trigonometric functions by utilizing the reflection principle.
Khan Academy
Khan Academy: Restrict Domains of Functions to Make Them Invertible
Given the graph of a function, find ways to restrict its domain in order to make it invertible. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.