Question

$1 + tan {}^{2}a \div 1 + cot {}^{2}a = (1 - tan \: a \: \div1 - cot \: a) { }^{2}$

Answer 1

here is your answer buddy....
(1+tan²a)/1+cot²a=sec²a/cosec²a

(1/cos²a)/(1/sin²a)=sin²a/cos²a

=>tan²a
i hope it helps