Cos (x+135) = sin x. Nilai tan x adalah...

cos (x + 135°) = sin x
cos x cos 135 - sin x sin 45 = sin x
-1/2 √2 (cos x + sin x) = sin x
(cos x + sin x)/sin x = - 2/√2
cos x /sin x + 1 = -√2
cos x/sin x = -√2 - 1
sin x/cos x = -1/(√2 + 1)
tan x = -(√2 - 1)
tan x = 1 - √2