In the old version of Maple, the accurate value of Sin()and Cos() at some particular points, such as Pi/10, can be returned as below:

But in Maple 18, it just returns the same as the input.

How to make Maple18 return the accurate value as before?

Here is the ODE:

dsolve((y(x)^2-x)*(D(y))(x)+x^2-y(x) = 0, {y(x)})

And the Maple 18 returns a very complex result.

But as we know,the more elegant result should be this:

How can I get this simple result with Maple?

ode := diff(sqrt(U(t)), t) = sqrt(U__0)-sqrt(U(t))

ics := U(0) = 0

dsolve({ics, ode})

And the result maple returns is U(t)=0 !