Лекция 7. Тригонометричнифункции ...



7. . .

: , , 3

:

(0; 90) 9. .

a

b

sin a

cos b

sin = , cos = , tg =

= , ctg =

=

c

c

cos b

sin a

sin2 + cos2 = 1, tg . ctg = 1

sin(90 - ) = cos , cos(90 - ) = sin , tg(90 - ) = ctg

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( 1 , Oxy). . O, Ox, OM ( ).

. O, . M , .. , , . + 360, + 2.360 .., .

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:

y = sin x y = cos x x [-1; 1], ..

-1 sin x 1, -1 cos x 1 x R.

(1)

y = sin x y = cos x 2,

..

sin(x + 2k) = sin x, cos(x + 2k) = x, k Z.

(2)

, , x [0; 2) y = sin x x [-; ] y = cos x.

y = sin x e , y = cos x , ..

sin(-x) = - sin x, cos(-x) = cos x.

(3)

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