共50条信息
在\(\vartriangle ABC\)中,点\(D\)在边\(AB\)上,\(CD\bot BC,\ AC=5\sqrt{3},\ \) \(CD=5,\ \) \(BD=2AD\),则\(AD\)的长为 .
已知,则\(\cos (2α+ \dfrac{3π}{5}) \)
已知曲线\(C\)的极坐标方程为\({ρ}^{2}= \dfrac{1}{3co{s}^{2}θ+si{n}^{2}θ} \),以极点为平面直角坐标系的原点,极轴为\(x\)轴的正半轴建立平面直角坐标系.
\((1)\)求曲线\(C\)的普通方程;
\((2)\)\(A\)、\(B\)为曲线\(C\)上两个点,若\(OA\)\(⊥\)\(OB\),求\( \dfrac{1}{|OA{|}^{2}}+ \dfrac{1}{|OB{|}^{2}} \)的值。
计算\(\dfrac{\cos {{10}^{0}}-\sqrt{3}\cos (-{{100}^{0}})}{\sqrt{1-\sin {{10}^{0}}}}=\) \(.(\)用数字做答\()\)
进入组卷