Rút gọn biểu thức sau:
1.$A=cos(5\Pi -x)-sin(\frac{3\Pi}{2}+x)+tan(\frac{3\Pi}{2}-x)+cot(3\Pi-x)$
2.$B=\frac{sin(a+5\Pi)}{cos(\frac{\Pi}{2}-a)}.\frac{tan(\Pi-a)}{cot(a+3\Pi)}.\frac{cos(a+3\Pi)}{cos(\frac{3\Pi}{2}-a)}$
Rút gọn biểu thức sau:
1.$A=cos(5\Pi -x)-sin(\frac{3\Pi}{2}+x)+tan(\frac{3\Pi}{2}-x)+cot(3\Pi-x)$
2.$B=\frac{sin(a+5\Pi)}{cos(\frac{\Pi}{2}-a)}.\frac{tan(\Pi-a)}{cot(a+3\Pi)}.\frac{cos(a+3\Pi)}{cos(\frac{3\Pi}{2}-a)}$
Có thể tiến chậm, nhưng đừng bao giờ bước lùi – Abraham Lincoln
PVTT
Rút gọn biểu thức sau:
1.$A=cos(5\Pi -x)-sin(\frac{3\Pi}{2}+x)+tan(\frac{3\Pi}{2}-x)+cot(3\Pi-x)$
2.$B=\frac{sin(a+5\Pi)}{cos(\frac{\Pi}{2}-a)}.\frac{tan(\Pi-a)}{cot(a+3\Pi)}.\frac{cos(a+3\Pi)}{cos(\frac{3\Pi}{2}-a)}$
1. ĐK: ................
$A=\cos(5\pi -x)-\sin\left (\frac{3\pi}{2}+x \right )+\tan\left (\frac{3\pi}{2}-x \right )+\cot\left (3\pi-x \right )\\=\cos\left ( \pi-x \right )+\sin\left ( \frac{\pi}{2}+x \right )-\tan\left ( x+\frac{\pi}{2} \right )+\cot\left ( \pi-x \right )\\=-\cos x+\cos x+\cot x-\cot x\\=0$
2. Đk:.............
$B=\frac{\sin(a+5\pi)}{\cos(\frac{\pi}{2}-a)}.\frac{\tan(\pi-a)}{\cot(a+3\pi)}.\frac{\cos(a+3\pi)}{\cos(\frac{3\pi}{2}-a)}\\=\frac{-\sin a\tan a\left (-\cos a \right )}{\sin a\left (-\cot a \right )\left ( -\sin a \right )}=\tan^2a$
Với chú ý $\tan x\cot x=1$
0 members, 1 guests, 0 anonymous users