# Find Exact Value of Trigonometric Expression...2

Discussion in 'Geometry and Trigonometry' started by nycmathguy, Dec 24, 2021.

1. ### nycmathguy

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Section 5.4  2. Is there a better, faster approach to solving this type of messy problem? If so, can you show me by completely working out 39 step by step?

Thank you.

nycmathguy, Dec 24, 2021
2. ### MathLover1

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correct

39. since tan(9pi/8)=tan(pi/8)

then tan(9pi)/8)-tan(pi/8)=0

=> =0

MathLover1, Dec 25, 2021
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3. ### nycmathguy

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What do you mean tan(9•pi/8) = tan(pi/8)?

Why does tan(9pi)/8) - tan(pi/8) = 0?

nycmathguy, Dec 25, 2021
4. ### MathLover1

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tan(9π/8)=tan(π/8+π) = tan (π/8)

Why does tan(9pi)/8) - tan(pi/8) = 0?-> substitute tan (π/8)
tan (π/8)- tan(pi/8) = 0

MathLover1, Dec 25, 2021
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