题目
77.下列式子正确的有（）A. sin^2pi+cos^2pi=1B. sin(pi)/(2)+cos(pi)/(2)-sinpi=0C. sin45^circcdotcos45^circ=(1)/(2)D. sin225^circ=-(sqrt(2))/(2)
77.下列式子正确的有（）
A. $\sin^{2}\pi+\cos^{2}\pi=1$
B. $\sin\frac{\pi}{2}+\cos\frac{\pi}{2}-\sin\pi=0$
C. $\sin45^{\circ}\cdot\cos45^{\circ}=\frac{1}{2}$
D. $\sin225^{\circ}=-\frac{\sqrt{2}}{2}$
题目解答
答案
ACD
A. $\sin^{2}\pi+\cos^{2}\pi=1$
C. $\sin45^{\circ}\cdot\cos45^{\circ}=\frac{1}{2}$
D. $\sin225^{\circ}=-\frac{\sqrt{2}}{2}$
A. $\sin^{2}\pi+\cos^{2}\pi=1$
C. $\sin45^{\circ}\cdot\cos45^{\circ}=\frac{1}{2}$
D. $\sin225^{\circ}=-\frac{\sqrt{2}}{2}$