Числа. 20 и 13
20+13=33
20-13=7.
))
(7,2a-1,6b)-(3,4b+2,2a-3)=
7,2a-1,6b-3,4b-2,2a+3=5a-5b+3
A) (cosa + sina)^2 - 2 sina*cos a = (cos^2 a + 2 sina*cos a + sin^2) - 2 sin 1.
a*cosa= =cos^2 + sin^2 a = 1.
б)(sina - cos a)^2 + 2 sina*cos a=sin^2 a - 2 sina*cosa + cos^2 a + 2 sina* cosa=
= sin^2 + cos^2 a = 1.
2.
a) sin2x*cos2x= 1/2 * sin 4x; *2;
2 sin2x* cos2x= sin4x.
sin(2*2x) = sin 4x;
sin 4x= sin 4x.
б)sin x/2 * cos x/2 = 1/2 * sinx; *2;
2 sin x/2 * cos x/2 = sin x;
sin( 2* x/2) = sin x;
sin x = sin x
Lg0,005=lg5*0,001=lg5+lg0,001=0,7+(-3)=-2,3
Решение задания приложено