What two pieces of evidence show that Juliet is dedicated and intelligent?

After Juliet learns that her new husband, Romeo, has killed her cousin, Tybalt, her thoughtful response showcases her intelligence.  She knows that she should love her husband, but she should also hate the man who killed her kinsman.  Her wordplay and use of oxymora (compact paradoxes that are comprised of two conflicting words) to accurately capture her conflicting feelings about Romeo illustrates how smart she is.  Juliet says,

O serpent heart hid with a flowering face!

Did ever dragon keep so fair a cave?

Beautiful tyrant! Fiend angelical!

Dove-feathered raven, wolvish-ravening lamb!

Despisèd substance of divinest show,

Just opposite to what thou justly seem’st.

A damnèd saint, an honorable villain! (3.2.74-80)

She laments that his handsome face and sweetness seems to have masked his inner fiend, that he is truly dangerous even though he appears to be kind and loving.  To be so articulate in such a moment of deep grief, especially at thirteen years old, is surely a mark of intelligence beyond her years.

Then, after Juliet has been told that she must marry the County Paris in two days or her parents will leave her to beg and die in the streets for her disobedience, she goes to Friar Lawrence's cell to ask him for help.  While there, her words prove her dedication to Romeo.  She would rather die than be disloyal to him, and she is dedicated to finding a way for them to be together despite his banishment and her impending nuptials to Paris.  She says, in part,

Give me some present counsel, or, behold,

'Twixt my extremes and me this bloody knife

Shall play the umpire, arbitrating that

Which the commission of thy years and art

Could to no issue of true honor bring. (4.1.63-67)

She asks him to give her advice about what to do, or else she will use her dagger to resolve the conflict between what she wants to do and what she is being forced to do.  In other words, if he cannot cannot, in his wisdom, discern another honorable way for her to resolve the conflict, she will kill herself.  If this isn't dedication, I don't know what is.