SOLUTION: What is the exact value of tan 105 degrees? I did the work but find myself lost on what I was doing in showing the work. Here's what I got. tan(45+60) so then I used a sum diffe

Question 807653: What is the exact value of tan 105 degrees? I did the work but find myself lost on what I was doing in showing the work. Here's what I got.
tan(45+60)
so then I used a sum difference formula
=tan(45)tan(60)/(1-tan(45)tan60) The top I got radical 3 plus 1 and bottom is -radical 3 plus 1 I tried on the calculator but it gave me negative(-) radical 3 minus 1 divided by 2. What did I do wrong?
Answer by fcabanski(1391) (Show Source): You can put this solution on YOUR website!
tan(x+y) does not = tan(45)tan(60)/(1-tan(45)tan(60)

The identity is tan(x+y) = (tan(x) + tan(y))/(1-tan(x)tan(y))

You multiplied instead of added (in the numerator).

RELATED QUESTIONS
what is the exact value of Tan(105... (answered by Alan3354)

Use the addition identity to find the exact value for tan 105 degrees. Show the... (answered by Alan3354)

Find the exact value of tan(105�) (answered by Edwin McCravy)

tan 5pi/3 and i need to determine the exact value of the expression without a calculator. (answered by richard1234)

Find the Exact value (No Decimals) of sin(105 degrees) using the sum or difference... (answered by Theo)

please explain or show work. this exactly how the question was written. using the... (answered by lwsshak3)

Coulkdnt find exactly what i need help with but I am working on factoring and having... (answered by scott8148)

Use sum or difference identity to find the exact value of tan 105... (answered by lwsshak3)

I have two questions. One of them I came up with an answer, but am not sure if it is... (answered by Alan3354)