cos(2A) + cos(2A) cot(2A) = cot(2A)
cos(2A) + cos(2A) cot(2A) - cot(2A) = 0
cot(2A) sin(2A) + cos(2A) cot(2A) - cot(2A) = 0
cot(2A) (sin(2A) + cos(2A) - 1) = 0
cot(2A) = 0 or sin(2A) + cos(2A) - 1 = 0
cot(2A) = 0 or sin(2A) + cos(2A) = 1
cot(2A) = 0 or sin(2A) cos(π/4) + cos(2A) sin(π/4) = 1/√2
cot(2A) = 0 or sin(2A + π/4) = 1/√2
[2A = cot⁻¹(0) + nπ] or
[2A + π/4 = sin⁻¹(1/√2) + 2nπ or 2A + π/4 = π - sin⁻¹(1/√2) + 2nπ]
(where n is any integer)
[2A = π/2 + nπ] or
[2A + π/4 = π/4 + 2nπ or 2A + π/4 = 3π/4 + 2nπ]
[A = π/4 + nπ/2] or
[2A = 2nπ or 2A = π/2 + 2nπ]
[A = π/4 + nπ/2] or
[A = nπ or A = π/4 + nπ]
A = (1 + 2n) π/4 or A = nπ or A = π/4 + nπ
