15. (sin 3x + sin x) sin x +(cos 3x - cos x) cos x = 0 prove that
Answers
Answered by
3
Answer:
Step-by-step explanation:
See below
Explanation:
(
sin
3
x
+
sin
x
)
sin
x
+
(
cos
3
x
−
cos
x
)
cos
x
=
sin
3
x
sin
x
+
sin
2
x
+
cos
3
x
cos
x
−
cos
2
x
=
sin
3
x
sin
x
+
cos
3
x
cos
x
−
(
cos
2
x
−
sin
2
x
=
cos
2
x
−
cos
2
x
0
, as required
Answered by
1
First take LHS and learn formulas of trigo
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