如图,抛物线 y =- x 2 +1与 x 轴的正半轴交于点 A ,将线段 OA 的 n 等分点从依次记为 P 1 , P 2 ,…, P n -1 ,过这些分点分别作x轴的垂线,与抛物线的交点依次为 Q 1 , Q 2 ,…, Q n -1 ,从而得到 n -1个直角三角形△ Q 1 OP 1 , △ Q 2 P 1 P 2 ,…, △ Q n -1 P n -1 P n -1 ,当 n →∞时,这些三角形的面积之和的极限为 .
【简答题】根据句意及所给中文提示、首字母或英文解释,写出句中所缺单词。 1. Lucy is studying in a ___________ (混合的) school. 2. I love the ___________ (味道) of chocolate. 3. I __________ (想知道) when and where they will have a picnic. 4. My aunt ...
【简答题】根据句意及所给中文提示、首字母或英文解释,写出句中所缺单词。 1. Lucy is studying in a ___________ (混合的) school. 2. I love the ___________ (味道) of chocolate. 3. I __________ (想知道) when and where they will have a picnic. 4. My aunt ...