Question

please help me ....
​I want full solution

Answer 1

Answer:

Cos⁴A - Sin⁴A

(Cos²A)² - (Sin²A)²

(Cos²A +Sin²A) (Cos²A-Sin²A)

1(Cos²A -Sin²A)

1-Sin²A-Sin²A = 1-2Sin²A

Cos²A - (1-Cos²A) .

2Cos²A - 1.

Hence, Option D is correct!!