Question

Помогите, пожалуйста

Answer 1

2sina + 2sinacosa

---------------------------

2sina - 2sinacosa

2sina(1+cosa)

--------------------

2sina(1-cosa)

1+cosa

-----------

1-cosa

ctg²(a/2)

cos²(a/2)

--------------

sin²(a/2)

1-sin²(a/2)

---------------

sin²(a/2)

1-1/4

------

1/4

0,75/0,25 = 3

Answer 2

Ответ:

3

Объяснение:

(2sin a + sin 2a) / (2sin a - sin 2a) =

= (2sin a + 2 sin a cos a) / (2sin a - 2 sin a cos a) =

= 2 sin a(1+cos a) / 2sin a(1-cos a)=

=(1+cos a) / (1-cos a)=

=(1+1-2sin²(a/2)) / (1-1+2sin²(a/2))=

=(2-2sin²(a/2)) / 2sin²(a/2)=

=(1-sin²(a/2)) / sin²(a/2)=

= 1 / sin²(a/2) - sin²(a/2)/sin²(a/2) =

= 1 / sin²(a/2) - 1 =

= 1 / (1/2)² - 1 =

= 1 / (1/4) - 1 =

= 1 * 4/1 - 1 =

= 4 - 1 = 3