Answer: -45° = -(π/4)
<u>Step-by-step explanation:</u>
sin x + cos x = 0
sinx = -cos x <em>subtracted cos x from both sides</em>
<em>divided cos x from both sides</em>
tan x = -1 <em>simplified fraction</em>
tan⁻¹ (tan x) = tan⁻¹ (-1) <em>applied inverse tan to both sides</em>
x = tan⁻¹ (-1) <em>simplified</em>
x = -45°
<u>Easier method:</u>
sin x = -cos x
At which points are cos x and sin x opposites?
- <em>In Quadrant II at 135°</em>
- <em>In Quadrant IV at 315 (which equals -45°)</em>
Inverse tan is only valid in Quadrants IV and I so the answer is -45°