1.

cos(450° + a) = cos(360° + 90° + a) = cos(90° + a) (2 четверть) = sin(a)

2cos(450° + a) - sin(a) = 2sin(a) - sin(a) = sin(a)

2.

[tex] \sin( \frac{7\pi}{6} ) = \sin(\pi + \frac{\pi}{6} ) = - \sin( \frac{\pi}{6} ) = - 0.5[/tex]

-0,5 - 1 = - 1,5

Ответ: 2) [ - 2 ; - 1 )

3.

4cos²a = 1

cos²a = 1/4

sin²a + cos²a = 1

sin²a = 1 - cos²a = 1 - 1/4 = 4/4 - 1/4 = 3/4

4sin²a = 4 × 3/4 = 3