This inverse-trig answer is x/2 only because of the domain

Most students and teachers mechanically solve the question discussed inside this video without giving any importance to what is the DOMAIN of x given. Watch this video to understand the significance of giving importance to the DOMAIN of x. -- For learning Physics or Maths from me... for 11th and 12th class Indian syllabus, you can write to me on the following email: Email = howtostudy2021@gmail.com