Math, asked by gourav9349, 8 months ago

Prove that cos^3 2x + 3 cos 2x = 4 (cos^6 x - sin^6 x)

Answers

Answered by amarchetry917

1

Step-by-step explanation:

cosxcos2xcos4xcos8x=

16sinx

sin16x

Take L.H.S

=

2

1

sinx[(2sinxcosx)cos2xcos4xcos8x]

=

2

1

sinx(sin2xcos2xcos4xcos8x)

=

4

1

sinx[(2sin2xcos2x)cos4xcos8x]

=

4

1

sinx(sin4xcos4xcos8x)

=

8

1

sinx(sin8xcos8x)

=

16

1

sinx(2sin8xcos8x)

=

16

1

sinx(sin16x)

=

16sinx

sin16x

Proved

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