SOLUTION: Use sum or difference identity to find the exact value of tan 105 degrees

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Question 644038: Use sum or difference identity to find the exact value of tan 105 degrees
Answer by lwsshak3(11628) About Me  (Show Source):
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Use sum or difference identity to find the exact value of tan 105 degrees
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Identity: tan(s+t)=(tan s+tan t)/(1-tan s tan t)
For given problem:
tan (105º)=tan(45+60)
=(tan 45+tan 60)/(1-tan 45 tan 60)
=(1+√3)/(1-1*√3)
tan(105º)=(1+√3)/(1-√3)
check with calculator:
(1+√3)/(1-√3)≈-3.732..
tan (105º)≈-3.732..