prove that sin 5x – 2sin 3x & sina
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Step-by-step explanation:
sinC−sinD=2cos(
2
C+D
)sin(
2
C−D
)
cosC−cosD=−2sin(
2
C+D
)sin(
2
C−D
)
LHS=
cos5x−cosx
sin5x−2sin3x+sinx
=
cos5x−cosx
(sin5x−sin3x)−(sin3x−sinx)
=
−2sin3xsin2x
2cos4xsinx−2cos2xsinx
=
−2sin3xsin2x
2sinx(cos4x−cos2x)
=
−2sin3x(2sinxcosx)
2sinx(−2sin3xsinx)
=
cosx
sinx
=tanx=RHS
LHS=RHS
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