Raw_input In if-statement? [duplicate]

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• How do I test one variable against multiple values? 13 answers

I'd like to be able to use raw_input put in by the user in an if statement, but I have no idea how to do it. Here, I ask them for raw input and if they type, "yes", I want to print, "Your triangle is:". if they type, "no", I want to print "Thank you for your time." Is there a way to do this? Please see my code below:

tri=raw_input("Do the points that you entered form a triangle? (yes or no)")  
tri=str(tri)  

if tri == "yes" or "Yes" or "YES":   
    print "Your triangle is an:"  
elif tri == "no" or "NO" or "No":  
    print "Thank you for your time."  
else:  
    print "Not a valid answer, please try again later."