SOLUTION: Use an Addition or Subtraction Formula to write the expression as a trigonometric function of one number, and find its exact value.
sin 4pi/7 cos 5pi/21 - cos 4pi/7 sin 5pi/21
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-> SOLUTION: Use an Addition or Subtraction Formula to write the expression as a trigonometric function of one number, and find its exact value.
sin 4pi/7 cos 5pi/21 - cos 4pi/7 sin 5pi/21
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Question 871086: Use an Addition or Subtraction Formula to write the expression as a trigonometric function of one number, and find its exact value.
sin 4pi/7 cos 5pi/21 - cos 4pi/7 sin 5pi/21 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.
sin 4pi/7 cos 5pi/21 - cos 4pi/7 sin 5pi/21
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Identity:sin(x-y)=sinx*cosy-cosx*siny=sin(4π/7-5π/21)=sin(12π/21-5π/21)=sin(7π/21)=sin(π/3)=√3/2
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