Jika cos 2x = 3/8. Tentukan nilai . a. Sin 2x b. Tan 2x c. Tan 1/2x d. Sin 6x

tg x = sin x / cos xRumus
ctg x = cos x / sin x
csc x = 1 / sin x
sec x = 1 / cos x
ctg = 1 / tg x

sin² x + cos² x = 1
tg² x + 1 = sec² x
ctg² + 1 = csc² x
sin 2x = 2 sin x cos x
cos 2x = cos² x - sin² x = 2 cos² x - 1 = 1 - 2 sin² x
tan 2x = (2 tan x) / (1 - tan² x)
sin 3x = 3 sin x - 4 sin³ x
cos 3x = 4 cos³ x - 3 cos x
tan 3x = (3 tan x - tan³ x)/(1 - 3 tan² x)
1 - cos x = 2 sin² ½x
1 + cos x = 2 cos² ½x
1 ± sin x = 1 ± cos (½π - x)

KUADRAN I
cos (90 – x)˚ = sin x
tg (90 – x)˚ = ctg x
ctg (90 – x)˚ = tg x

KUADRAN II
sin (90 + x)˚ = cos x
cos (90 + x)˚ = –sin x
tg (90 + x)˚ = –ctg x
ctg (90 + x)˚ = –tg x
sin (180 – x)˚ = sin x
cos (180 – x)˚ = –cos x
tg (180 – x)˚ = –tg x
ctg (180 – x)˚ = –ctg x

KUADRAN III
sin (180 + x)˚ = –sin x
cos (180 + x)˚ = –cos x
tg (180 + x)˚ = tg x
ctg (180 + x)˚ = ctg x
sin (270 – x)˚ = –cos x
cos (270 - x)˚ = –sin x
tg (270 – x)˚ = ctg x
ctg (270 – x)˚ = tg x

KUADRAN IV
sin (270 + x)˚ = –cos x
cos (270 + x)˚ = sin x
tg (270 + x)˚ = –ctg x
ctg (270 + x)˚ = –tg x
sin (360 – x)˚ = –sin x
cos (360 – x)˚ = cos x
tg (360 – x)˚ = –tg x
ctg (360 – x)˚ = –ctg x

JUMLAH DAN SELISIH DUA SUDUT
sin (A + B) = sin A cos B + cos A sin B
sin (A – B) = sin A cos B – cos A sin B
cos (A + B) = cos A cos B – sin A sin B
cos (A – B) = cos A cos B + sin A. sin B
tg (A + B) = (tan A + tan B) / (1 – tan A tan B)
tg (A – B) = (tan A – tan B) / (1 + tan A tan