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 c++ function for calculating the approximate area of a circle.
user
double calculatecirclearea(double radius)
{
    const double pi = 3.14159;
    return pi * radius * radius;
}
assistant