Rewrite the expression so that there is no denominator:
(tan2x)/(cscx+1)

Sin^2(x) + cos^2(x) = 1 

cosec(x) = 1/sin(x), so divide  by sin^2(x): 

1 + cot^2(x) = cosec^2(x) 
cot^2(x) = cosec^2(x) - 1 
= (cosec(x) - 1)(cosec(x) + 1). 

If we multiply top and bottom  fraction by (cosec(x) + 1) 

(cosec(x) + 1) tan^2(x) / (cosec(x) - 1)(cosec(x) + 1) 
= (cosec(x) + 1) tan^2(x) / cot^2(x). 

Now tan(x)
=1/cot(x) so tan^2(x)
=1/cot^2(x) 

(cosec(x) + 1) tan^2(x) tan^2(x
= (cosec(x) + 1) tan^4(x) . 
(cosec(x) + 1) tan^4(x).

Ithink number to is 1 inch=5 miles