Question

Обчисліть cos960° срочно)

Answer 1

Cos(960°) = cos(360•3 -120°) = cos(120°) = -cos(60°) = -½.

Ответ: минус одна вторая

Answer 2

Sure, to calculate cos(960°), we can use the periodicity property of the cosine function.

Cosine has a period of 360 degrees (or 2π radians), which means that the cosine of an angle is equal to the cosine of that angle minus any multiple of 360 degrees.

So, cos(960°) can be written as:

cos(960°) = cos(960° - 3 * 360°)

Now, 960° - 3 * 360° = 960° - 1080° = -120°

The cosine of -120° can be obtained using the trigonometric identity:

cos(-θ) = cos(θ)

Therefore, cos(960°) = cos(-120°)

Now, we can find the exact value of cos(-120°):

cos(-120°) = cos(-π/3) ≈ -0.5

So, cos(960°) ≈ -0.5.