Sin x =1/(5^-1/2) Nilai dari cos x - 5cos(90+x) + 2sin(180-x)

trigonometri

sin x =1/(5¹/²) = 1/√5
cos x = √(1  - sin² x)
cos x = √(1 - 1/5) = √(4/5) = 2/√5

cos x  - 5 cos (90 + x)  + 2 sin (180-x) =
= cos x - 5 {-sin x } + 2 sin x
= cos x + 5 sin x + 2 sin x
= cos x + 7 sin x
= 2/√5 + 7 (1/√5)
= 9/√5
= 9/√5  x √5/√5
= ⁹/₅ √5