Известно, что ctg a = -3 и а - угол IV четверти. Найдите ѕin а.

1) sin(45°+L)=sin(45°)*cos(L)+cos(45°)*sin(L)=√2/2*sin(L)+√2/2*cos(L)
2) cos(45°+L)=cos(45°)*cos(L)-sin(45°)*sin(L)=√2/2*cos(L)-√2/2*sin(L)
3) cos(3L) = cos(L)*cos(2L)-sin(L)*sin(2L) = cos(L)*(2cos²(L)-1)-sin(L)*2sin(L)*cos(L) = 2cos³(L)-cos(L)-2cos(L)*sin²(L) = 2cos³(L)-cos(L)-2cos(L)*(1-cos²(L)) = 2cos³(L)-cos(L)-2cos(L)+2cos³(L) = 4cos³(L)-3cos(L)
4) sin(3L) = sin(L)*cos(2L)+sin(2L)*cos(L) = sin(L)*(1-2sin²(L))+2sin(L)*cos(L)*cos(L) = sin(L)-2sin³(L)+2sin(L)*cos²(L) = sin(L)-2sin³(L)+2sin(L)*(1-sin²(L)) = sin(L)-2sin³(L)+2sin(L)-2sin³(L)=3sin(L)-4sin³(L)

1) = 2+а+6+3а = 4а+8 = 4(а+2)
2) = 3 - а+6 - 2а = 9 - 3а = 3(3 - а)
3) = (m - n)(1 - 5) = - 4(m - n) = 4(n - m)
4) = (x - y)(1 - 4) = - 3(x - y)  = 3(y - x)
5) = (a+b)(4b+1)
6) = (x+y)(5x+1)
7) = (x-y)(a+1)
8)  = (m - n)(c+1)
9) = (a - b)+2(a - b) = (a - b)(1+2) = 3(a -b)
10) = (c - d)(1+3) = 4(c - d)
11) = 2(a - b)+c(a - b) = (a - b)(2+c)
12) = (c - d)(3 - a)
13) смотри 11
14) = (c - d) (3 +a)
15) = (x - e)(1+a)
16) = (m+n)(1+b)
17) = (x - y)(2+a)
18) = 3(m - n) - b(m - n) = (m - n)(3 - b)
19) = ([x+y)(2 - a)
20) = (m+n)(3 - b)