SOLUTION: cot(105°)*tan(15°)

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Question 759298: cot(105°)*tan(15°)
Answer by lwsshak3(11628) About Me  (Show Source):
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cot(105°)*tan(15°)
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Identity:tan%28x%2By%29=%28tan%28x%29%2Btan%28y%29%29%2F%281-tan%28x%29tan+%28y%29%29

cot(105º)=1/tan(105º)=-1/(2+√3)
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Identity:tan%28x-y%29=%28tan%28x%29-tan%28y%29%29%2F%281%2Btan%28x%29tan+%28y%29%29

tan(15º)≈2-√3
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cot(105°)*tan(15°)=
Calculator check:
tan(105º)≈-3.73
exact value=-(2+√3)≈3.73
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tan(15º)≈0.2679
exact value=2-√3≈0.2679