Trigonometric Identities (Class X)                                                               Mathematics
DPP
             1         1
1.                           2 sec 2 A
         1  sin A 1  sin A
           sin      1  cos 
2.                             2cosec                                                  (CBSE 2000)
           cos      sin 
         1  cos A     sin A
3.                 
           sin A     1  cos A
4.       cos ec2   sec 2   cos ec 2 sec2                                            [CBSE 2001)
5.       Prove the following identities :                                                 (CBSE 2000)
         (i)     (sin  + cosec  )2 + (cos  + sec  )2 = 7 + tan2  + cot2 
         (ii)    (sin  + sec  )2 + (cos  + cosec  )2 = (1 + sec  cosec  )2          (CBSE 2000)
                 sin   cos  sin   cos         2             2             2
         (iii)                                                                        (CBSE 2000)
                 sin   cos  sin   cos  sin2   cos 2  2sin2   1 1  2 cos 2 
         (iv)    (cosec  – sin  ) (sec  – cos  ) (tan  + cot  ) = 1
         (v)     tan2  + cot2  + 2 = sec2  cosec2 
6.       Prove the following identities :
                 sin2  cos 2      1
         (i)                             2
                 cos  sin  sin  cos 2 
                    2      2      2
                 (1  sin )2  (1  sin )2      1  sin2  
         (ii)                                 2             
                           cos 2                         2
                                                    sin  
                 (1  cot   tan )(sin   cos )
         (iii)                                       sin2  cos 2 
                         sec 3   cosec 3 
7.       cosec6  = cot6  + 3cot2  cosec2  +1
                              1          1
8.       (1  tan2 A)  1                                                                 (CBSE 2006)
                            tan A  sin A  sin4 A
                                2       2
                          2                     2
                    1                           1  sin2  
9.        tan              tan             2
                  cos            cos          sin2  
                                                                
10.      Prove the following identities :
                 sin   2sin3 
         (i)                        tan                                                    (CBSE 2018)
                 2 cos 3   cos 
                       1           1     1         1
         (ii)                                                                              (CBSE 2002)
                 cosec   cot  sin  sin  cosec   cot 
         (iii)   2(sin6   cos 6 )  3(sin4   cos 4 )  1  0
         (iv)    (sin8   cos 8 )  (sin2   cos 2 )(1  2sin2  cos 2 )