h Exercises 15-24, use the fundamental identities and appropriate algebraic Operations to simplify each expression. 15. (1+tan x)(1 - tan x) + sec x 16. (secx-1) (sec x + 1) - tan x 17. (secx+tan x) (sec x - tan x) sec x - 4 18. sec x-2 19. csc x- cotx 20. sin x cos x(tan x + cot x) sec x csc x(sin x + cos x) 21. secx+csC x 1 1 22. CSC x+1 CSC x 1 - tan2 X - 2 tan x - 3 23. 24. tan x + 1 tan secx - 1 x + sec x-1