Tolong bantu yah Diketahui 2 cos x = 3 tan x dengan - phi/2 <x<phi/2. Nilai cos x + tan x adalah
whongaliem 2.cos x = 3.tan x 2.cos x = 3 .sin x / cos x 2.cos² x = 3.sin x 2 (1 - sin² x) = 3.sin x 2 - 2.sin² x = 3.sin x 0 = 2.sin² x + 3.sin x - 2 0 = (2.sin x - 1)(sin x + 2) 2.sin x - 1 = 0 atau sin x + 2 = 0 2.sin x = 1 atau sin x = - 2 (tak memenuhi) sin x = 1/2
cos² x + sin² x = 1 cos² x + (1/2)² = 1 cos² x + 1/4 = 1 cos² x = 1 - 1/4 cos² x = 3/4 cos x = √(3/4) cos x = (1/2)√3
cos x + tan x = cos x + sin x / cos x = [ (1/2)√3 + 1/2 ] / (1/2)√3 = 1 + (1/√3) = 1 + (1/3)√3
2.cos x = 3 .sin x / cos x
2.cos² x = 3.sin x
2 (1 - sin² x) = 3.sin x
2 - 2.sin² x = 3.sin x
0 = 2.sin² x + 3.sin x - 2
0 = (2.sin x - 1)(sin x + 2)
2.sin x - 1 = 0 atau sin x + 2 = 0
2.sin x = 1 atau sin x = - 2 (tak memenuhi)
sin x = 1/2
cos² x + sin² x = 1
cos² x + (1/2)² = 1
cos² x + 1/4 = 1
cos² x = 1 - 1/4
cos² x = 3/4
cos x = √(3/4)
cos x = (1/2)√3
cos x + tan x = cos x + sin x / cos x
= [ (1/2)√3 + 1/2 ] / (1/2)√3
= 1 + (1/√3)
= 1 + (1/3)√3