2006-II-44
答案:A
$\begin{array}{rcl}
3\cos^2 x -4\cos x +1 & =
… Read $\begin{array}{rcl}
3\cos^2 x -4\cos x +1 & =
留意正四面體的每個面均為邊長為 $3\text{ cm}$ 的等邊三角形。考慮其底三角形 $ABC$
$\begin{array}{ll}
OB=OC & \te
在 $\Delta OAB$ 中,
$\begin{array}{ll}
OB = BA
$\begin{array}{cl}
= & \left( \dfrac{-
留意 $CD$ 的長度
$\beg
$\begin{array}{|c|c|c|c|} \hline
& F
$\begin{array}{cl}
= &
$\begin{array}{cl}
= & \dfrac{10a+1