cos x=0,2 , x lancip tentukan sin(x-30)

jawab

cos x = 0,2 = 2/10 = 1/5 = x/r
y²  = r² - x²
y² = 5² - 1²
y² = 25-1= 24
y =  √24 = 2√6
sin x = y/r = 2√6 /(5)= 2/5  √6

sin (x - 30) = sin x cos 30  - cos x sin 30
= (2/5 √6)( 1/2 √3) - (1/5)(1/2)
= 1/5 √18 - 1/10
= 1/5 (3√2)  - 1/10
= 3/5 √ 2 - 1/10
= 1/10  (6 √2 - 1)