Question

use an addition or subtraction formula to find the exact value of the expression

tan(255degrees)
So far i got tan(135+120)
tan135+tan120/1-tan135tan120

Answer 1

hi callisto

Answer 2

If you don't mind, can I introduce you a new combination of 225?

Answer 3

That would make life easier..

Answer 4

sure

Answer 5

its 255 by the way

Answer 6

Yes. 225 = 180 + ___?

Answer 7

What is that ___?

Answer 8

its 255 not 225

Answer 9

Sorry!!!

Answer 10

tan(135+120)
tan135+tan120/1-tan135tan120
^Fine enough!
What's the problem?

Answer 11

it is tan135tan120/1-tan135tan120

Answer 12

i dont know how to find tan 135 and 120

Answer 13

Hmmm....
\[tan(x+y) = \frac{tanx+tany}{1-tanxtany}\]
So, tan135+tan120/1-tan135tan120 is fine.

tan135 = tan (180 - 45) = -tan45 = ...
Similar for tan120

Answer 14

ok

Answer 15

now what

Answer 16

Can you find tan135 and tan120?

Answer 17

-root 3 and -1

Answer 18

Plug the numbers you got into tan135+tan120/1-tan135tan120 and simplify it.
Note: tan135 = -1 and tan120 = -sqrt3