Warnings about conversions

[Kings]

I keep getting warnings about variable conversions, but dunno how to fix them. Can someone have a look and possibly fix it for me (very easy code)?

Warnings:

main.cpp(10) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
main.cpp(19) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
main.cpp(57) : warning C4244: 'argument' : conversion from 'int' to 'float', possible loss of data
main.cpp(59) : warning C4244: 'argument' : conversion from 'int' to 'float', possible loss of data

Code:

#include <iostream.h> // input output


#define PI 3.14159

// Function for calculating the area of a circle
float area (float r)
{
	float a;
	a = PI * r * r;

	return(a);
}

// Function for calculating the circumference of a circle
float circumference (float r)
{
	float a;
	a = 2 * PI * r;

	return(a);
}

// Program start
int main ()
{
	// Declare needed variables
	int type;
	float answer;
	int n = 0;
	int radius;

	//Keep looping until a valid choice has been made
	do {
		cout << "What would you like to calculate?\n";
		cout << "1. Circumference\n";
		cout << "2. Area\n";
		cout << "Enter your choice: ";
		cin >> type;

		// Check if a valid choice has been made
		if (type == 1 || type == 2) {
			// A valid choice has been made, exit loop
			break;
		} else {
			// Invalid choice, display error
			cout << "Invalid Choice! Please try again\n\n";
		}
	} while (n != 1);

	// Ask for radius
	cout << "Please enter a radius for the circle: ";
	cin >> radius;

	// Use the functions to calculate
	if (type == 1) {
		answer = circumference(radius);
	} else if (type == 2) {
		answer = area(radius);
	}

	//Display answer
	cout << "The answer is: " << answer;

	//Exit Program
	return 0;
}