Question

Cos 25 cos65 -sin25 sin 65​

Answer 1

Ответ:

Cos(25+65)

Cos(90)

Answer 2

To simplify the expression $\cos(25^\circ) \cos(65^\circ) - \sin(25^\circ) \sin(65^\circ)$, you can use the trigonometric identity for the cosine of the difference of two angles:

$\cos(A - B) = \cos(A) \cos(B) + \sin(A) \sin(B)$

In this case, let $A = 65^\circ$ and $B = 25^\circ$. So, we have:

$\cos(65^\circ - 25^\circ) = \cos(40^\circ)$

Now, you can calculate $\cos(40^\circ)$ using your calculator or a trigonometric table. Once you find the value, that will be your answer.