Use the compound and double formulae to write the following in terms of A only sin3A(use sin A only)?

1 Answer
Ratnaker Mehta
Mar 23, 2018

Please refer to the Explanation.

Explanation:

#sin3A=sin(2A+A)#,

#=sin2AcosA+cos2AsinA#,

#=(2sinAcosA)cosA+(1-2sin^2A)sinA#,

#=2sinAcos^2A+sinA-2sin^3A#,

#=2sinA(1-sin^2A)+sinA-2sin^3A#,

#=2sinA-2sin^3A+sinA-2sin^3A#.

# rArr sin3A=3sinA-4sin^3A#.

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