Sin=opo/hyp ||

Cos=adj/hyp ||

Tan=opo/adj ||

Ctn=adj/opo ||

Sec=hyp/adj ||

Csc=hyp/opo ||

If you see its always the sen/tan/sec followed by its covalue. From the third onward it becomes the inverse

Sin= 1/Csc; Cos=1/Sec: Tan=1/Ctn and the reverse also applies.

The inverse of a fraction is when you exchange the places of the denominator and numerator