Question

Solve for x. -sin(x)-cos(x)=0

Answer 1

Simplify the equation,
\[\tan x=-1\] And then,
\[x=-\pi/4 + \pi k, \ \ k\in \mathbb{Z}\]

Answer 2

how does that simplify to tan x? is that a trig identity?

Answer 3

You should know that the angle that makes tan x=1 is pi/4. So to obtain tan x=-1, must be -pi/4.

Alternatively, you can use the calculator, to find arctan(-1), to obtain -45 degrees or -pi/4.

Answer 4

I just don't understand how you got tan x from -sin(x)-cos(x).. I know how to solve tan x=1.

Answer 5

because your answer is incorrect when I do it on the calculator. -sinx-cosx does not equal tan x?