Question

-sin 9pi/4 это сколько? ​

Answer 1

Ответ:

-$-\frac{\sqrt{2} }{2}$

Пошаговое объяснение:

-sin ($\frac{9\pi }{4}$) = -sin2 $\pi$ + $\frac{\pi }{4}$ = -sin $\frac{\pi }{4}$ = - $\frac{\sqrt{2} }{2}$

Answer 2

Ответ: минус корень из двух на два

Пошаговое объяснение:на картинке

Answer 3

To find the value of -sin(9pi/4), we can use the trigonometric identity:

sin(x) = sin(x + 2kπ)

where k is an integer. This identity tells us that the sine function has a periodicity of 2π.

In this case, 9π/4 is equivalent to 2π + π/4. So, we can rewrite -sin(9π/4) as -sin(2π + π/4).

Now, since the sine function is negative in the second and third quadrants of the unit circle, we can find the reference angle in the first quadrant, which is π/4. Then, we determine the sign based on the quadrant:

In the first quadrant: sin(π/4) = √2/2 In the second quadrant: sin(π + π/4) = sin(5π/4) = -√2/2 In the third quadrant: sin(2π - π/4) = sin(7π/4) = -√2/2

Since 9π/4 is in the third quadrant, the value of -sin(9π/4) is -(-√2/2) = √2/2.

Therefore, -sin(9π/4) = √2/2.