Question

sin x-sin 3x÷cos²- cos²x=2sin x​

Answer 1

Answer:

LHS :

sin

2

x−cos

2

x

sinx−sin3x

=

−(cos

2

x−sin

2

x)

2sin(

2

x−3x

)cos(

2

x+3x

)

=

−cos2x

2sin(−x)cos2x

=

−cos2x

−2sinxcos2x

=2sinx

= RHS