Question

basics!!................ clear them..

Answer 1

1st part is correct.

you have just taken negative sign on both sides.

in 2nd part,
why did you equate it to 0?

you can't simply equate it to 0

1/ coses a sec a

= sin a cos a

= 1/2 sin 2a

you can simplify it like that..
______________

1/ coses a sec a = 0

=> 1 = 0× coses a sec a

=> 1 = 0

which is not true. so equation is wrong.