TrigFcns - 1-masala yechimi | MathModel.uz

1.3-bo'lim : Trig funktsiyalari

1. Kalkulyatordan foydalanmasdan $\displaystyle \cos \left( {\frac{{5\pi }}{6}} \right)$ ning aniq qiymatini aniqlang.

Yechim

Birinchidan, biz $\pi - \frac{\pi }{6} = \frac{{5\pi }}{6}$ va shuning uchun $\frac{{5\pi }}{6}$ uchun terminal chizig'i ikkinchi kvadrantda manfiy $x$ o'qi bilan $\frac{\pi }{6}$ burchagini hosil qilishini payqashimiz mumkin va biz ushbu muammo uchun quyidagi birlik doirasiga ega bo'lamiz.

$A unit circle with the angles $\frac{\pi }{6}$, $\frac{\pi }{4}$ and $\frac{\pi }{3}$ drawn in the first quadrant and labeled with the coordinates $\left( {\frac{{\sqrt 3 }}{2},\frac{1}{2}} \right)$, $\left( {\frac{{\sqrt 2 }}{2},\frac{{\sqrt 2 }}{2}} \right)$ and $\left( {\frac{1}{2},\frac{{\sqrt 3 }}{2}} \right)$ where they meet the circle. The axes are labeled with the angles 0 and $2\pi $, $\frac{\pi }{2}$, $\pi $ and $\frac{{3\pi }}{2}$ and the points (1,0), (0,1), (-1,0) and (0,-1). The angle $\frac{{5\pi }}{6}$ is drawn in the second quadrant and a dashed horizontal line connects the point where it meets the circle to the point for $\frac{\pi }{6}$, showing the two points have the same $y$-coordinate and $x$-coordinates that differ only in sign.$

2-qadam

$\frac{{5\pi }}{6}$ ni ifodalovchi chiziq koordinatalari $\frac{\pi }{6}$ ni ifodalovchi chiziq koordinatalari bilan bir xil bo‘ladi, bundan tashqari $x$ koordinatasi endi manfiy bo‘ladi. Shunday qilib, bizning yangi koordinatalarimiz $\left( { - \frac{{\sqrt 3 }}{2},\frac{1}{2}} \right)$ bo'ladi va shuning uchun javob:

\[\cos \left( {\frac{{5\pi }}{6}} \right) = - \frac{{\sqrt 3 }}{2}\]