已知直线l1为曲线y=x2在点（1，1）处的切线，l2为该曲线的另一条切线，且l1⊥l2．
（1）求直线l1与l2的方程；
（2）求直线l1，l2与x轴所围成的三角形的面积．
（1）f′（x）=2x，∴f′（1）=2
∴直线l1的方程为y-1=2（x-1），即y=2x-1
设l2与曲线y=x2相切的切点为（x1，y1），∵l1⊥l2．
∴f′（x1）=2x1=-
，∴x1=-1 2
，∴y1=x12=1 4
，1 16
∴直线l2的方程为y-
=-1 16
（x+1 2
），即y=-1 4
x-1 2 1 16
（2）由
得直线l1与l2的交点坐标为（y=2x-1 y=-
x-1 2 1 16
，-3 8
），1 4
又直线l1，l2与x轴的交点分别为（
，0），（-1 2
，0）1 8
∴所求三角形的面积S=
|1 2
-（-1 2
）|×|-1 8
|=1 4
．5 64
| 信息匹配 | |
When speaking about renewable energy, we are talking about power which derives its energy from resources which will not be diminished from the use.Renewable energy is a substitute for the non－renewable energy of fossil f  uel.2._____ One fundamental advantage of renewable energy, and environmentalists' favorite reason to promote its use, is that there are no greenhouse gases or other pollutants give out as there are with the burning of fossil fuel  s.Renewable energy, or solar, water and wind power, are certainly not new although they havereceived much attention recently because they will not cause pollution.Environmental friendly power sources such as wind, solar an  d water power have been used in both developing and developed countries for a long time because they are cheap and clean, but they have yet to be used as a primary source of energy for any big urban area. 3._____ The generation of power from renewable energy sources has become somewhat more common in recent times as people have increasingly become aware of issues such as climate change due to fossil fuel by－products and the political or social worri  es about nuclear power.There are numerous countries and non－profit, environmentally conscious organizations that are supporting the use of renewable energy. 4._____ The flow of renewable energy has to do with naturally occurring phenomena.Tides, sunlight, wind and heat are all created by geothermal events and all are sources of energy has unique characteristics related to where and how we can use them. 5._____ Most technology which transforms renewable energy into power  which we can use is solar power either directly or indirectly.The atmospheric system of the earth keeps balance so that the heat which spreads out into space is equal to the amount of radiation received from the sun.The quantity of energy contained in the atmosphere approximates the earth' s climate.The bodies of water of the earth, or its hydrosphere, absorb much of the radiation which is received from the sun.And much of that absorbed radiation is in the lower latitudes surrounding the equator. |