SOLUTION: Derive the formula for tan(3A). please help me

Question 1076136: Derive the formula for tan(3A). please help me
Answer by Edwin McCravy(20065) (Show Source): You can put this solution on YOUR website!


We consider tan(3A) as tan(2A+A) and then
we use the formula for tan(a+b) which is this:



and we substitute 2A for a and A for b:



equation 1: 

But equation 1 is not enough, for we must now find tan(2A).

We find that by considering 2A as A+A and use this formula again



substituting A for a and also A for b:



Next we must substitute for tan(2A) in equation 1:

 

To simplify that compound fraction multiply top and bottom
by (1-tan²A)











Edwin

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