Question

Cos3b*cos5b*cos8bheeeeeelp​

Answer 1

Объяснение:

cos 2b/2+cos8b /2 это через дробь,но я не уверена что правильно

Answer 2

To simplify the expression cos(3b) * cos(5b) * cos(8b), you can use trigonometric identities.

Start by using the product-to-sum trigonometric identity:

cos(A) * cos(B) = 1/2 * [cos(A + B) + cos(A - B)]

So, applying this identity to your expression:

cos(3b) * cos(5b) = 1/2 * [cos(3b + 5b) + cos(3b - 5b)]

= 1/2 * [cos(8b) + cos(-2b)]

Now, you have cos(8b) and cos(-2b) in the expression. Cosine is an even function, which means cos(-x) = cos(x). So, cos(-2b) = cos(2b).

Now, your expression becomes:

1/2 * [cos(8b) + cos(2b)]

Next, apply the same product-to-sum identity to cos(8b) * cos(2b):

cos(8b) * cos(2b) = 1/2 * [cos(8b + 2b) + cos(8b - 2b)]

= 1/2 * [cos(10b) + cos(6b)]

Now, your expression is:

1/2 * [cos(10b) + cos(6b)]

So, the simplified expression is:

(1/2) * [cos(10b) + cos(6b)]

You can leave it in this form, or if you need further simplification or specific values, you can substitute values for b as needed.