Answer:
dc/dt = 3.6cm/s
Explanation:
Let c be the length of the diagonal:
[tex]c=\sqrt{x^2+y^2}[/tex] The rate at which c is changing is:
[tex]\frac{dc}{dt} =\frac{2*x*\frac{dx}{dt} +2*y*\frac{dy}{dt}}{2*\sqrt{x^2+y^2} }[/tex]
where:
x=5cm dx/dt=2cm/s
y=8cm dy/dt=3cm/s
[tex]\frac{dc}{dt} =3.6cm/s[/tex]
