sin3x=3sinx-4sincubex prove RHS=LHS
Answers
Answered by
1
Answer:
x = 30. LHS : - sin3(30) = sin90 = 1. RHS : - 3sin(30) - 4{sin3(30)}^2 = 3 × 1/2 - 4(sin90)^2 = 3/2 - 4 = -5/2. LHS =/= RHS .
Answered by
0
Answer:
Since the angle sum formula of sine is:
sin
(
α
+
β
)
=
sin
α
cos
β
+
cos
α
sin
β
,
and the double angle formula of cosine:
cos
(
2
α
)
=
cos
2
α
−
sin
2
α
=
2
cos
2
α
−
1
=
1
−
2
sin
2
α
then:
sin
(
3
x
)
=
sin
(
2
x
+
x
)
=
sin
(
2
x
)
cos
x
+
cos
(
2
x
)
sin
x
=
=
(
2
sin
x
cos
x
)
⋅
cos
x
+
(
1
−
2
sin
2
x
)
sin
x
=
=
2
sin
x
cos
2
x
+
sin
x
−
2
sin
3
x
=
=
2
sin
x
(
1
−
sin
2
x
)
+
sin
x
−
2
sin
3
x
=
=
2
sin
x
−
2
sin
3
x
+
sin
x
−
2
sin
3
x
=
=
3
sin
x
−
4
sin
3
x
Similar questions