frac3英语

（1）设OQ=a，则OA+AP=3a，OC=$\sqrt{{OA}^{2}+{AC}^{2}}$=5，（1分）∵AC∥OB，∴△ORQ∽△CRP，（2分）∴$\frac{OQ}{PC}=\frac{OR}{RC}$，∴PC=$\frac{3}{2}a$，∵OA+AC=7，即3a+$\frac{3}{2}a$=7，∴$a=\frac{14}{9}$，（4分）AP=$\frac{5}{3}$，（5分）∴P点坐标（$\frac{5}{3}$，3），Q点坐标（$\frac{14}{9}$，0），设直线PQ的函数关系式为y=kx+b，∴$\left\{\begin{array}{l}\frac{5}{3}k+b=3\\ \frac{14}{9}k+b=0\end{array}\right.$解得$\left\{\begin{array}{l}k=27\\ b=-42\end{array}\right.$所以直线PQ的函数关系式是y=27x-42；（8分）（2）当0$≤t≤\frac{15}{7}$时，点P在OA上，点Q在OB上，S=$\frac{1}{2}$×OQ×OP=$\frac{12}{25}{t}^{2}$，当$\frac{15}{7}≤t≤5$时，点P在AC上，点Q在OB上，S=$\frac{1}{2}$×$OQ×BC=\frac{6}{5}t$，（4分）当5$＜t≤\frac{70}{11}$时，点P、Q都在BC上，S=$\frac{1}{2}×PQ×OB$=28-$\frac{22}{5}t$．（6分）

forwardad.1. 向前He hurried forward to meet her.他赶紧走上前去迎接她。2. 向将来;今后They never met from that day forward.他们从那天以后再也未能相见。3. 提前The meeting had been put forward an hour.会议提前一小时举行。4. 出来;(现)出He put forward a new view.他提出了一种新见解。a.1. 前面的[Z][B]We can see the forward part of the ship.我们可以看见船的前部。2. 早的;提前的;早熟的The spring flowers are rather forward this year.今年春天的花儿开得相当早。3. 鲁莽的,冒失的;放肆的She made a forward remark.她讲了一句冒昧的话。4. 热心的,乐意的He's always forward with help.他总是乐于助人。n.1. 前锋vt.1. 转交[(+to)]Would you please forward this letter to his new address?请你把这封信转寄到他的新地址。2. 发送,递送[(+to)][O1]The goods will be forwarded to your house.这些货将发送到你家里。3. 促进,助长He tried to forward his father's plan.他努力想促成父亲的计划