+0  
 
+4
877
2
avatar+115747 
Hi everyone,
I know that i am just being lazy or blind or both but the last question on this sheet eludes me.
Can someone help please.

140211 Tom's question.jpg
 Feb 11, 2014
 #1
avatar+6226 
0
You need to show that T and U have the same y coordinate.

T has y coordinate apq
U has y coordinate -apr

but if you look at the coordinates of P and Q and note that PQ is perpendicular to the axis of the parabola then it should be clear that q = -r

so both T and U have y coordinates apq and thus TU is horizontal and thus perpendicular to the vertical parabola axis.
 Feb 11, 2014
 #2
avatar+115747 
+5
Rom:

You need to show that T and U have the same y coordinate.

T has y coordinate apq
U has y coordinate -apr

but if you look at the coordinates of P and Q and note that PQ is perpendicular to the axis of the parabola then it should be clear that q = -r

so both T and U have y coordinates apq and thus TU is horizontal and thus perpendicular to the vertical parabola axis.



Of course, thanks Rom, much appreciated.
 Feb 11, 2014

32 Online Users

avatar
avatar