Show that cotx=√(csc^2x-1) is not an identity
sin^2x + cos^2x = 1
divide by sin^2 and you have
1 + cot^2x = csc^2x
so it appears that cotx=√(csc^2x-1)
but in QII and QIV cotx < 0 but √(csc^2x-1) is positive
divide by sin^2 and you have
1 + cot^2x = csc^2x
so it appears that cotx=√(csc^2x-1)
but in QII and QIV cotx < 0 but √(csc^2x-1) is positive