Помогите с 5 и 4 пожалуйста

4. sin(60) = (3)/2
cos(45) = (2)/2,
tg(30) = 1/(3)
(6)*sin(60)*cos(45) + (3)*tg(30) = (6)*( (3)/2 )*( (2)/2 )+(3)*(1/3) = 
 = ((6)*(6)/4 ) + 1 = (6/4) + 1 = (3/2)+1 = (3+2)/2 = 5/2 = 2,5.

5. sin(a) = 3/5.
cos(a) + sin(a) = 1,
cos(a) = 1 - sin(a),
cos(a) = (1 - sin(a)) = (1 - (3/5)) = (25 - 9)/5 = (16)/5 = 4/5
или cos(a) = -(1-sin(a)) = -4/5.
tg(a) = sin(a)/cos(a)
tg(a) = (3/5)/(4/5) = 3/4
либо tg(a) = (3/5)/(-4/5) = -3/4.
ctg(a) = cos(a)/sin(a),
ctg(a) = (4/5)/(3/5) = 4/3
или ctg(a) = (-4/5)/(3/5) = -4/3.