
Mike M. answered 07/20/23
PhD Tutor in Mathematics
First, note that the left-hand side simplifies as follows:
sec x csc x (tan x + cot x)
= (1/cos x) (1/sin x) [(sin x/cos x) + (cos x/sin x)]
= (1/cos x) (1/sin x) (sin x/cos x) + (1/cos x) (1/sin x)(cos x/sin x)
= 1/cos2x + 1/sin2x = sec2x + csc2x
Now use the fact that 1 + tan2x = sec2x and 1 + cot2x = csc2x.
Please let me know if you need further clarification (i.e., more details on the last part).