1. Write a program in C++ to enter two angles of a triangle and find the third angle. (For a triangle, if the 1st angle is x degree and the 2nd angle is y degree, the 3rd angle is (180-x-y) degree.) Sample Output: Find the third angle of a triangle : Input the 1st angle of the triangle : 20 Input the 2nd angle of the triangle: 25 The 3rd of the triangle is : 135