#include #include class shape { protected: double x,y; public: virtualvoid get_data()=0; virtualvoid display_area()=0; }; class triangle : public shape { public: void get_data(void) { cout<<\"\ \ =====Data Entry for Triangle=====\ \ \"; cout<<\"Enter base and height respectively : \"; cin>>x>>y; } void display_area(void) { cout<<\"\ \ =====Area of Triangle=====\ \ \"; double aot; aot = 0.5 * x * y; cout<<\"Area of Triangle is \"<>x>>y; } void display_area(void) { cout<<\"\ \ =====Area of rectangle=====\ \ \"; double aor; aor = x * y; cout<<\"Area of Rectangle is \"<>choice; switch(choice) { case 1 : list[0]->get_data(); list[0]- >display_area(); getch(); break; case 2 : list[1]->get_data(); list[1]- >display_area(); getch(); break; case 3 : goto end; default: cout<<\"\ \ Invalid choice\ Try again\ \"; getch(); } } end: } Solution #include #include class shape { protected: double x,y; public: virtualvoid get_data()=0; virtualvoid display_area()=0; }; class triangle : public shape { public: void get_data(void) { cout<<\"\ \ =====Data Entry for Triangle=====\ \ \"; cout<<\"Enter base and height respectively : \"; cin>>x>>y; } void display_area(void) { cout<<\"\ \ =====Area of Triangle=====\ \ \"; double aot; aot = 0.5 * x * y; cout<<\"Area of Triangle is \"<>x>>y; } void display_area(void) { cout<<\"\ \ =====Area of rectangle=====\ \ \"; double aor; aor = x * y; cout<<\"Area of Rectangle is \"<>choice; switch(choice) { case 1 : list[0]->get_data(); list[0]- >display_area(); getch(); break; case 2 : list[1]->get_data(); list[1]- >display_area(); getch(); break; case 3 : goto end; default: cout<<\"\ \ Invalid choice\ Try again\ \"; getch(); } } end: }.

1. A) At the center, the path travelled by the sounds waves from the two speakers will be the same
==> No path difference.
Since the two waves were initialy in phase, the phase difference between the two waves for the
observer at center will be zero (additional phase difference = 2 x pi x path
difference/wavelength).
B) Now suppose the observer mooved towards one of detectors by a distance d, then the path
difference between the two waves will be 2d (as one has to travel d more and the other has to
travel d less)
==> for destructive interference, phase difference = 2 x pi x path difference/wavelength = pi
path difference = 2d ; wavelength = speed of sound / frequency = 343/(171.5) = 2m
==> d= wavelength/4 ; = 2/4 = 0.5 m = 50 cm
Solution
A) At the center, the path travelled by the sounds waves from the two speakers will be the same
==> No path difference.
Since the two waves were initialy in phase, the phase difference between the two waves for the
observer at center will be zero (additional phase difference = 2 x pi x path
difference/wavelength).
B) Now suppose the observer mooved towards one of detectors by a distance d, then the path
difference between the two waves will be 2d (as one has to travel d more and the other has to
travel d less)
==> for destructive interference, phase difference = 2 x pi x path difference/wavelength = pi
path difference = 2d ; wavelength = speed of sound / frequency = 343/(171.5) = 2m
==> d= wavelength/4 ; = 2/4 = 0.5 m = 50 cm