Verified answer

Объяснение:

1.

A) sin190° <0

Б) tg175° <0

В) соs 410° =соs 50° >0

Г) tg860°=140° <0

Д) соs(-116) <0

E) sin830°=sin110° >0

2.

A) sin(-π/6)= -1/2

Б) соs(-π/3)= 1/2

B) tg(-π/4)= -tg(π/4)= -1

Г) соs(-π/2)=0

3.

A)

sinα=√2/3 ; 0<α<π/2

sin²α+cos²α=1

cosα=√(1-sin²α)=√(1-(√2/3)²)=

=√(1-2/9)=√(7/9)=√7/3

tgα=sinα/cosα=(√2/3)/(√7/3)=√2/√7

ctgα=cosα/sinα=(√7/3)/(√2/3)=√7/√2

Б)

соs=15/17 ; 3π/2<α<2π

sin²+cos²α=1

sinα=√(1-cos²α)=√(1-(15/17)²)=

=√(1-(225/289)=√(64/289)=8/17

sin в 4 четверти отрицательный,то

sinα= -8/17

tgα=sinα/cosα=(-8/17)/(15/17)= -8/15

ctgα=1/tgα= 1/(-8/17)= - 17/8