cos (2 * a) = (1 - tg^2 a)/(1 + tg^2 a);
cos (2 * a) = (1 - sin^2 a/cos^2 a)/(1 + sin^2 a/cos^2 a);
cos (2 * a) = ((cos^ 2 - sin^2 a)/cos^2 a)/((cos^2 a + sin^2 a)/cos^2 a);
cos (2 * a) = (cos^2 a - sin^2 a)/cos^2 a * cos^2 a/(cos^2 + sin^2 a);
cos (2 * a) = (cos^2 a - sin^2 a)/1 * 1/(cos^2 + sin^2 a);
cos (2 * a) = (cos^2 a - sin^2 a)/(cos^2 + sin^2 a);
cos (2 * a) = (cos^2 a - sin^2 a)/1;
cos (2 * a) = cos^2 a - sin^2 a;
cos (2 * a) = cos (2 * a);
Значит, тождество верно.
Пошаговое объяснение:
1.x =9 ; x = - 1
3.x = 5,5 ; x = -9,5
5.x = 2 ; x = 3 ;
2.x = 10 ; x = -6
4.x= 6 1/3 ; x = - 3 2/3
6.x = -5 ; x = 6 ; x = -6
Пошаговое объяснение:
1.|x - 4| = 5
x - 4 = 5 x - 4 = -5
x = 5 + 4 x = -5 + 4
x = 9 x = -1
3.|2x + 4| = 15
2x + 4 = 15 2x + 4 = -15
2x = 15 - 4 2x = -15 - 4
2x = 11 2x = -19
x = 11 : 2 x = -19 : 2
x = 5,5 x = -9,5
5.(2 - x)|x - 3| = 0
2 - x = 0 |x - 3| = 0
-x = -2 x - 3 = 0
x = 2 x = 3
2.|x - 2| = 8
x - 2 = 8 x - 2 = -8
x = 8 + 2 x = -8+2
x = 10 x = -6
4. |3х - 4| =15
3x - 4 = 15 3x - 4 = -15
3x = 15 + 4 3x = -15 + 4
3x = 19 3x = -11
x = 19 : 3 x = -11 : 3
x = 6 1/3 x = - 3 2/3
6.(x +5)lx - 6|=0
x + 5 = 0 |x - 6| = 0
x + 5 = 0 x - 6 = 0
x = -5 x = 6
-(1,9×0,6)=1,14
Пошаговое объяснение:
(-)×(+)=(-)