b part
P(-4,0) R(2,0) (一開始係比 (x+1)^2-9)
If Q is a moving point on the graph and below x axis
S is a point above x axis
PQRS is a parallelogram
A(x) is the area of PQRS
1.find the domain of PQRS
2.find the maximum area of PQRS
作者: -終場ソ使者- 時間: 2-12-2011 19:31
1)
You prove AE//OM
<ADO=<DAO
<DOM=<ADO
<MOB=<DAO
<DOM=<MOB
2.1)
Domain (for x) is -4<x<2
2.2)
To find max of A(x),
just consider the height of tri. PRQ (PR is its base)
since PR is a constant, A'(x) is directly prop. to its height (A'(x) represents the area of tri. PRQ)
ie find the max height
therefore, A(x)=2A'(x)作者: 天才A 時間: 3-12-2011 13:59 本帖最後由 天才A 於 3-12-2011 14:01 編輯
我prove唔到AE//OM...
果時剩5分鐘 就係掙扎係度...
不過今日聽人講先發現可以用 similar triangle AEB OMB....
1)
You prove AE//OM
-終場ソ使者- 發表於 2-12-2011 19:31
第2題解得好好
唔該晒....
我竟然傻到連domain 都寫唔到
救命作者: -終場ソ使者- 時間: 13-12-2011 20:15
in fact mid-pt thm may be a better for proving AE//OM !作者: 天才A 時間: 14-12-2011 19:21
in fact mid-pt thm may be a better for proving AE//OM !
-終場ソ使者- 發表於 13-12-2011 20:15
