In the sentence

Have you ridden the fastest roller coaster at the amusement park.

Is the verb thence past perfect?

5 answers

verb thence??

What is the verb?
Is the verb tense past perfect?
No.

https://owl.english.purdue.edu/owl/resource/601/01/

http://englishplus.com/grammar/00000361.htm
So present perfect.

What about this one?

We have tried every possible solution.

Also present perfect?
Yes. Both are present perfect.