7+8+9=24см
24см/4=6см- сторона квадрата
S(квадрата)=6*6=36(см²)
14. y'(x)=y'(t)/x'(t)
y'(t)=3-3cos(3t+2)/sin(3t+2)
x'(t)=3-3sin(3t+2)/cos(3t+2)
y'(x)=(3-3ctg(3t+2))/(3-3tg(3t+2))=-ctg(3t+2)
13.
-2*2*cos(2x+5)sin(2x+5)=3x^2y^10+x^3*10y^9*y'+7
-2sin(4x+10)=3x^2y^10+10x^3y^9y'+7
y'=-(2sin(4x+10)-3x^2y^10-7)/(10x^3y^9)
5 · у + 4 · 3 = 37
5у + 12 = 37
5у = 37-12
5у = 25
у = 5