Question

(tan70+tan80)/(1-tan70*tan80)

Answer 1

I think this is the formula for tan(A + B)

Answer 2

\(\bf tan({\color{brown}{ \alpha}} \pm {\color{blue}{ \beta}}) = \cfrac{tan({\color{brown}{ \alpha}})\pm tan({\color{blue}{ \beta}})}{1\mp tan({\color{brown}{ \alpha}})tan({\color{blue}{ \beta}})}\)

any ideas?

Answer 3

- if my memory serves me right!

Answer 4

so your expression = tan (70+ 80) = tan 150 degrees

Answer 5

no

Answer 6

note the tan is negative in the second quadrant

Answer 7

thanks

Answer 8

@cwrw238 Yeah, you're correct. Realized I read the formula wrong. The sign in the fraction should be opposite not the same :P Thx!

Answer 9

(tan(7pi/24)-tan(pi/8))/(1+tan(7pi/24)*tan(pi/8)

Answer 10

yw @Lyrae

Answer 11

What does that mean?

Answer 12

you are welcome