SOLUTION: Use an Addition or Subtraction Formula to write the expression as a trigonometric function of one number and find its exact value. (tan pi/18 + tan pi/9)/(1-tan pi/18 tan pi/9)

Question 871087: Use an Addition or Subtraction Formula to write the expression as a trigonometric function of one number and find its exact value.
(tan pi/18 + tan pi/9)/(1-tan pi/18 tan pi/9)

Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
Use an Addition or Subtraction Formula to write the expression as a trigonometric function of one number and find its exact value.
(tan pi/18 + tan pi/9)/(1-tan pi/18 tan pi/9)
Identity:tan(x+y)=tanx+tany/1-tanx*tany
(tan π/18 + tan π/9)/(1-tan π/18 tan π/9)=tan(π/18+π/9)=tan(3π/18=tan(π/6)=√3/3
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