1.

Assertion (A): cos^(3)x+cos^(3)(120^(@)+x)+cos^(3)(120^(@)-x)=3/4cos3x Reason (R ): costheta+cos(120^(@)+theta)+cos(120^(@)-theta)=0 and costheta.cos(120^(@)+theta).cos(120^(@)-theta)=1//4 cos 3 theta

Answer»

A is true, R is true and R is CORRECT explanation of A
A is true, R is true and R is not correct explanation of A
A is true, R is false
A is false, R is true

Answer :A


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