



 
Hi Sam, I am going to assume that you know the expressions for sine, cosine and tangent of A + B. There is some information in our answer to an earlier question. Start by writing tan(3A) as tan(2A + A) and use the expression for tan(A + B) to get Now replace tan(2A) by 2tan(A)/(1tan^{2}(A)) To simplify this expression, multiply the numerator and denominator by 1tan^{2}(A) and the expression becomes Simplification of this expression gives Penny  


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