Question

(1 - cos a)×(1 + cos a)=

Answer 1

Ответ:

(1 - cos a)×(1 + cos a)= 1 - cos^2a = sin^2a

Answer 2

Let's simplify the expression (1 - cos a) × (1 + cos a):

Using the identity (a - b)(a + b) = a^2 - b^2, we can rewrite the expression as:

(1 - cos a) × (1 + cos a) = (1^2 - cos^2 a)

Now, using the identity cos^2 a + sin^2 a = 1, we can substitute cos^2 a with (1 - sin^2 a):

(1 - cos a) × (1 + cos a) = (1^2 - (1 - sin^2 a)) = (1 - 1 + sin^2 a) = sin^2 a

Therefore, the simplified expression is sin^2 a.