Question

plz tick correct option and proper method

Answer 1

option "b" is the correct answer

Answer 2

OPTION:C is correct.
 We know that,
   cosec^2theata - cot^2 theata = 1
   a^2 - b^2=(a+b)(a-b)
   in the same way
     (cosec theata + cot theata )(cosec theata - cot theata) = 1
       given
 cosec theata - cot theata = a ............ >eq 1
     so
           ( cosec theata + cot theata).a=1
               cosec theata + cot theata = 1/a ............>eq 2
         by adding equations 1 and 2 we get
         2cosec theata = a+1/a
       therefore,  cosec theata = 1/2 (a+1/a)