题干

选修4-4:坐标系与参数方程

在直角坐标系xOy中,曲线C的参数方程为 {x=2cosαy=2+2sinα (α为参数),直线l的参数方程为 {x=3
3
2
t
y=3+
1
2
t
(t为参数),在以坐标原点O为极点,x轴为正半轴为极轴的极坐标系中,过极点O的射线与曲线C相交于不同于极点的点A,且点A的极坐标为(2 3 ,θ),其中θ∈(
π
2
,π)
(Ⅰ)求θ的值;
(Ⅱ)若射线OA与直线l相交于点B,求|AB|的值.
上一题 下一题 0.0难度 选择题 更新时间:2020-01-23 11:44:22

答案(点此获取答案解析)

解:(Ⅰ)曲线C的参数方程为 {x=2cosαy=2+2

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                                                                   Tips for Cooking on a Tight Schedule

     From my experience,there are three main reasons why people don't cook more often:ability,money and time.____ Money is a topic I'll save for another day.So today I want to give you some wisdom about how to make the most of the time you spend in the kitchen.Here are three tips for great cooking on a tight schedule:

     1.Think ahead.The moments when I think cooking is a pain are when I'm already hungry and there is nothing ready to eat.So think ahead of the coming week.When will you have time to cook? Do you have the right materials already?____      

     2.Make your time worth it.When you do find time to cook a meal,make the most of it and save yourself time later on.Are you making one loaf of bread?____ It takes around the same amount of time to make more of something.So save yourself the effort for a future meal.

     3.____ This may surprise you,but one of the best tools for making cooking worth your time is experimentation.It gives you the chance to hit upon new ideas and recipes that can work well with your appetite and schedule.The more you learn and the more you try,the more ability you have to take control of your food and your schedule.

     Hopefully that gives you a good start.____ And don't let a busy schedule discourage you from making some great changes in the way you eat and live!

A.Try new things.

B.Ability is easily improved.

C.Make three or four instead.

D.Understand your food better.

E.Cooking is a burden for many people.

F.Let cooking and living simply be a joy rather than a burden.

G.A little time planning ahead can save a lot of work later on.