C++之系統函數

引入系統函數 #include <cmath>

例： 求輸入角度的三角函數值

#include <iostream>
#include <cmath>
using namespace std;
const double PI = 3.1415;

int main(){
	double angle;
	cout << "please enter an angle:";
	cin >> angle;

	double radian = angle * PI / 180;

	cout << "sin(" << angle << ")=" << sin(radian) << endl;
	cout << "cos(" << angle << ")=" << cos(radian) << endl;

	return 0;
}