Question

Naidite sinx*cosx*cos2x , esli sin4x=4/9. proshu srochno !!!!!!

Answer 1

$sinxcosxcos2x=\frac{sin2xcos2x}{2}=\frac{sin4x}{4}=\frac{4}{4*9}=\frac{1}{9}$

Answer 2

Da, razumeem, naydëm znacheniye vyrajeniya sinx * cosx * cos2x, esli sin4x = 4/9.

Davayte naidyom znacheniye vyrajeniya:

Zametim, chto sin4x = (sin2x)^2, po etomu:

(sin2x)^2 = 4/9

Teper' prosto naydem sin2x:

sin2x = sqrt(4/9) = 2/3

Teper' naydem znacheniye vyrajeniya sinx * cosx * cos2x:

sinx * cosx * cos2x = sinx * cosx * cos(2 * 2x) = sinx * cosx * cos(4x)

Dlya polucheniya otveta, nuzhno znat' znacheniya sinx i cosx. No u menya net informatsii o znacheniyakh sinx i cosx, poetomu ya ne mogu tochno vydat' otvet.

Pozhaluysta, yavite znacheniya sinx i cosx, esli vy hotite poluchit' tochnyy otvet.