Answer: The length of STV is about 76.83 in.
Step-by-step explanation:
The length of an arc is given by :-
, where r= radius of the cirle,
is the central angke made by arc.
As per given , Radius of the circle : r= 20 in
Central angle of arc SCV = 
Then, Central angle of arc SCV = 
Then, the length of the arc STV =

Hence, the length of STV is about 76.83 in.