f4 maths

設0° ≤ x ≤ 360°


2tan(3x + 6°) =1
tan(3x + 6°) = 1/2
3x + 6° = 26.57°, (180+26.57)°, (360+26.57)°, (540+26.57)°, (720+26.57)°, (900+26.57)°
x = 6.88°, 66.86°, 126.86°, 186.86°, 246.86°, 300.86°


(√2)cos2x = 4cos(90° - 2x)
(√2)cos2x = 4sin2x
tan2x = (√2)/4
2x = 19.47°, (180+19.47)°, (360+19.47)°, (540+19.47)°
x = 9.74°, 99.74°, 189.74°, 279.74°


sin²x - 2sinxcosx - cos²x = 0
(sin²x - 2sinxcosx - cos²x)/cos²x = 0
tan²x - 2tanx - 1 = 0
tanx = {-(-2) ± √[(-2)² - 4(1)(-1)]}/2
tanx = (1 + √2), (1 - √2)
x = 67.5°, (180+67.5)°, (180-22.5)°, (360-22.5)°
x = 67.5°, 247.5°, 157.5°, 337.5°