Question

sinx + 2cosx = 0 where 0<=x<=2pi, what can x be equal to

Answer 1

sinx=-2cosx
sinx/cosx=-2
tanx=-2
Whatever x that fits tanx=-2

Answer 2

so I did \[\tan^{-1}(-2)\] and I got -1.107 which isn't correct

Answer 3

@nightwill

Answer 4

x has to be between 0 and 2pi, so -1.107 won't work.

Answer 5

the answer should be pi+arctan(-2) which is about 2.03444

Answer 6

Why did you add pi ?

Answer 7

I'm trying to refresh on trig

Answer 8

I added pi so that it fits in the domain. tan x has a period of pi, so tan x = tan (x+pi) Therefore,
\[\tan(tan^{-1}-2)=tan(\pi+tan^{-1}-2)\]