prove that sinA.sin(B−C)+sinB.sin(C−A)+sinC.sin(A−B)=0

sinA.sin(B-C)+sinB.sin(C-A)+sinC.sin(A-B)=0

Solution:-


L.H.S

= \sin A.\sin (B - C) + \sin B.\sin (C - A) + \sin C.\sin (A - B)

= \sin A(\sin B.\cos C - \cos B.\sin C) + \sin B(\sin C.\cos A - \cos C.\sin A)
                                     + \sin C(\sin A.\cos B - \cos A.\sin B)

= \sin A.\sin B.\cos C - \sin A.\cos B.\sin C + \sin B.\sin C.\cos A -
               \sin B.\cos C.\sin A + \sin C.\sin A.\cos B - \sin C.\cos A.\sin B

= 0 = R.H.S

\therefore L.H.S = R.H.S


                                                      \{ proved\}


How To Solve : -

  • In first step the formula of sin(a-b)=sina.cosb-cosa.sinb is putted.
  • This step is simply easy of multiplication.
  •  Arrange the following in regular manner and + and - terms are canceled out. 
  • Hence the Answer is 0
  • Finally we proved that sinA.sin(B-C)+sinB.sin(C-A)+sinC.sin(A-B)=0

Get Solution in Image Form :- 

prove that sinA.sin(B-C)+sinB.sin(C-A)+sinC.sin(A-B)=0


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