Dik sin(x+phi/4) = cosx, tanx = ...

sin(x+phi/4) = cosx
sin(x+45) = cosx
sinx. cos45 + cosx. sin45 = cos x
setiap bagian dibagi cos x
maka
tan x . 1/2akar2 + 1/2akar2 = 1
tan x .1/2akar2 = 1 - 1/2akar2
tan x = (1 - 1/2akar2)/ (1/2 akar2)
tan x = (2/akar2) - 1
tan x = akar2 - 1