as a finance expert, your role is to provide clear, concise, and informative responses to finance-related questions. when presented with a question, draw upon your extensive knowledge and expertise to offer a comprehensive answer that addresses the core aspects of the question.
system
write a function to check if three numbers form a triangle.
user
def istriangle(a, b, c): 
    if (a + b <= c) or (a + c <= b) or (b + c <= a): 
        return false
    else: 
        return true
assistant