tgA + 2cosA cscA = secA cscA + ctgA
                                    2        2
(senA / cosA) + 2cosA (1/senA) = [sen A + 2cos A]/(senA cosA) =
(tgA + ctgA)(cosA + senA) = cscA + secA
                                                     2       2
[(senA / cosA) + (cosA / senA)]( cosA + senA) = [(sen A + cos A)/(senA cosA)](cosA + senA) =

[1/(senA cosA)](cosA + senA) = cosA / (senA cosA) + senA / (senAcosA) = 1/senA + 1/cosA =

cscA + secA

  2           2       2       2
tg A – sen A = tg A sen A
      2           2       2           2       2     2            2       2
(sen A / cos A – sen A) = sen A [(1/cos A) – 1] = sen A (1 – cos A)/cos A =
      2       2       2           2       2
sen A sen A / cos A = sen A tg A


(secA – tgA)(cscA + 1) = ctgA

[(1/cosA) – senA/cosA][1/senA + 1] = [(1 – senA)/cosA][(1 + senA)/senA] =
          2                           2
(1 – sen A)/[senA cosA] = cos A / [senA cosA] = cosA / senA = ctgA


(1 – senA)(secA + tgA) = cosA
                                                                     2            2
(1 – senA)(1/cosA + sen/cosA) = (1 – senA)[1 + senA]/cosA = (1 – sen A)/cosA = cos A/cosA =
cosA


senA /(1 – cosA) = cscA + ctgA
                                                                             2
[senA (1 + cosA)] / [(1 – cosA)(1 + cosA)] = (senA + senA cosA)/(1 – cos A) =
2        2                      2
                   (senA + senA cosA)/sen A = senA/sen A + senAcosA/sen A = (1/senA) + cosA/senA = cscA + ctgA




                   tgA + 2cosA cscA = secA cscA + ctgA
                                                            2           2
                   (senA / cosA) + 2cosA (1/senA) = [sen A + 2cos A]/(senA cosA) =
                       2           2       2                           2
                   [sen A + cos A + cos A]/(senA cosA) = (1 + cos A)/(senA cosA) =
                                       2
                   1/(senA cosA) + cos A / (senA cosA) = cscA secA + ctgA



                   (tgA + ctgA)(cosA + senA) = cscA + secA
                                                                               2       2
                   [(senA / cosA) + (cosA / senA)]( cosA + senA) = [(sen A + cos A)/(senA cosA)](cosA + senA) =
                   [1/(senA cosA)](cosA + senA) = cosA / (senA cosA) + senA / (senAc




     a) Ctg x Sen x ≅ Cos x                        b) Sen y Sec y ≅ Tag y                              Tag x
                                                                                              c)             ≅ Sec x
                                                                                                       Sen x
d) Sec 2 x Ctg 2x ≅ Csc 2 x                            Cosx + Cotg x                          f) Sec 2 x ≅ Cosc x Sen x +     1
                                                   e)                 ≅ cos x
                                                         1 + cos c x                                                        Ctg 2 x
   Sen x Cos x Sec x                                              1    Sec x                  j) Tag x + Ctg x ≅ Sec x Csc x
h)         +       =                               i) Tag x +        ≅
   Cos x Sen x Sen x                                           Tag x Sen x
k) 2 Sec x Ctg x ≅ 2Csc x                          l) Sec A − Tag A Sen A ≅ Cos A             m)
                                                                                              (Sen x + Cos x )2 ≅ 2Sen x Cos x + 1
     Sen x + Tag x                                                       1                           Sen x    Cos x
ñ)                 ≅ Sen x                         o) Csc 2 x ≅                               p)            +       ≅ Csc x
       1 + Sec x                                                    1 − Cos 2 x                    1 + Cos x Sen x
q) Sen x (Csc x − Sec x ) ≅ 1 − Tag x              r) Sec 2 x − Sen 2 x =≅ Cos 2 x + Tag 2x        (              )
                                                                                              s) Sec 2 x − 1 Ctg 2 x ≅ 1
       2
           (
t) Sec x 1 − Sen x ≅ 12
                           )                       v) Cos x − Sen x ≅ 2Cos x − 1
                                                                2          2       2
                                                                                                       (
                                                                                              w) 1 + Ctg x Sen 2 x ≅ 1
                                                                                                              2
                                                                                                                      )
y) 1 − Tag A ≅ 2 − Sec A
               2               2
                                                      Sec x Ctg x                                 Cos x Sec x
                                                   z)             ≅ Sen x                     aa)             ≅ Ctg x
                                                        Csc 2 x                                      Tag x
(              )(       )
ab) 1 + Tag 2 A 1 − Cos 2 A ≅ Tag 2 A       ac)
                                                   Sec x Tag x
                                                        −      ≅1                             ad)
                                                                                                    1 + Ctg 2 y
                                                                                                                ≅ Ctg 2 y
                                                   Cos x Ctg x                                      1 + Tag 2 y
ae) (Ctg A + 1) + (Ctg A − 1) ≅ 2 Csc2 A
               2                2
                                            ad) 1 + cot 2 x ≅ cos c 2 x                       ah) (sec x + 1) (sec x − 1) ≅ tan g 2 x
ai) (Ctg x + tan gx ) ≅ Csc 2 x + sec 2 x         cos 2 x − tan g 2 x
                        2
                                                                                                    sen 2 x cos 2 x
                                            aj)                       ≅ cot g 2 x − sec 2 x   ak)          −        ≅ sec x
                                                            2
                                                        sen x                                        sen x   cos x

129 ejercicios resueltos sobre identidades trigonometrica

  • 2.
    tgA + 2cosAcscA = secA cscA + ctgA 2 2 (senA / cosA) + 2cosA (1/senA) = [sen A + 2cos A]/(senA cosA) =
  • 3.
    (tgA + ctgA)(cosA+ senA) = cscA + secA 2 2 [(senA / cosA) + (cosA / senA)]( cosA + senA) = [(sen A + cos A)/(senA cosA)](cosA + senA) = [1/(senA cosA)](cosA + senA) = cosA / (senA cosA) + senA / (senAcosA) = 1/senA + 1/cosA = cscA + secA 2 2 2 2 tg A – sen A = tg A sen A 2 2 2 2 2 2 2 2 (sen A / cos A – sen A) = sen A [(1/cos A) – 1] = sen A (1 – cos A)/cos A = 2 2 2 2 2 sen A sen A / cos A = sen A tg A (secA – tgA)(cscA + 1) = ctgA [(1/cosA) – senA/cosA][1/senA + 1] = [(1 – senA)/cosA][(1 + senA)/senA] = 2 2 (1 – sen A)/[senA cosA] = cos A / [senA cosA] = cosA / senA = ctgA (1 – senA)(secA + tgA) = cosA 2 2 (1 – senA)(1/cosA + sen/cosA) = (1 – senA)[1 + senA]/cosA = (1 – sen A)/cosA = cos A/cosA = cosA senA /(1 – cosA) = cscA + ctgA 2 [senA (1 + cosA)] / [(1 – cosA)(1 + cosA)] = (senA + senA cosA)/(1 – cos A) =
  • 4.
    2 2 2 (senA + senA cosA)/sen A = senA/sen A + senAcosA/sen A = (1/senA) + cosA/senA = cscA + ctgA tgA + 2cosA cscA = secA cscA + ctgA 2 2 (senA / cosA) + 2cosA (1/senA) = [sen A + 2cos A]/(senA cosA) = 2 2 2 2 [sen A + cos A + cos A]/(senA cosA) = (1 + cos A)/(senA cosA) = 2 1/(senA cosA) + cos A / (senA cosA) = cscA secA + ctgA (tgA + ctgA)(cosA + senA) = cscA + secA 2 2 [(senA / cosA) + (cosA / senA)]( cosA + senA) = [(sen A + cos A)/(senA cosA)](cosA + senA) = [1/(senA cosA)](cosA + senA) = cosA / (senA cosA) + senA / (senAc a) Ctg x Sen x ≅ Cos x b) Sen y Sec y ≅ Tag y Tag x c) ≅ Sec x Sen x d) Sec 2 x Ctg 2x ≅ Csc 2 x Cosx + Cotg x f) Sec 2 x ≅ Cosc x Sen x + 1 e) ≅ cos x 1 + cos c x Ctg 2 x Sen x Cos x Sec x 1 Sec x j) Tag x + Ctg x ≅ Sec x Csc x h) + = i) Tag x + ≅ Cos x Sen x Sen x Tag x Sen x k) 2 Sec x Ctg x ≅ 2Csc x l) Sec A − Tag A Sen A ≅ Cos A m) (Sen x + Cos x )2 ≅ 2Sen x Cos x + 1 Sen x + Tag x 1 Sen x Cos x ñ) ≅ Sen x o) Csc 2 x ≅ p) + ≅ Csc x 1 + Sec x 1 − Cos 2 x 1 + Cos x Sen x q) Sen x (Csc x − Sec x ) ≅ 1 − Tag x r) Sec 2 x − Sen 2 x =≅ Cos 2 x + Tag 2x ( ) s) Sec 2 x − 1 Ctg 2 x ≅ 1 2 ( t) Sec x 1 − Sen x ≅ 12 ) v) Cos x − Sen x ≅ 2Cos x − 1 2 2 2 ( w) 1 + Ctg x Sen 2 x ≅ 1 2 ) y) 1 − Tag A ≅ 2 − Sec A 2 2 Sec x Ctg x Cos x Sec x z) ≅ Sen x aa) ≅ Ctg x Csc 2 x Tag x
  • 5.
    ( )( ) ab) 1 + Tag 2 A 1 − Cos 2 A ≅ Tag 2 A ac) Sec x Tag x − ≅1 ad) 1 + Ctg 2 y ≅ Ctg 2 y Cos x Ctg x 1 + Tag 2 y ae) (Ctg A + 1) + (Ctg A − 1) ≅ 2 Csc2 A 2 2 ad) 1 + cot 2 x ≅ cos c 2 x ah) (sec x + 1) (sec x − 1) ≅ tan g 2 x ai) (Ctg x + tan gx ) ≅ Csc 2 x + sec 2 x cos 2 x − tan g 2 x 2 sen 2 x cos 2 x aj) ≅ cot g 2 x − sec 2 x ak) − ≅ sec x 2 sen x sen x cos x