Q21 of 44 Page 79

If x = 30°, then prove that

sin3x = 3sinx – 4 sin3x

For x= 30°,


LHS = sin (3×30°)


= sin (90°)


=1


RHS = 3sin30° - 4× (sin30°)3






Since LHS = RHS


sin3x = 3sinx – 4 sin3x


Hence proved.


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