3. Prove that: \(\left(cos{x}+cos{y}\right)^2+\left(sin{x}-sin{y}\right)^2=4{cos}^2{\frac{x+y}{2}}\).

Trigonometric Functions

Miscellaneous Exercise

ncert-solutions-class-11-chapter-2-trigonometric-functions-miscellaneous-exercise-question-3