Math Is Fun Forum

Monox D. I-Fly

Member

From: Indonesia

Registered: 2015-12-02

Posts: 2,000

[ASK] Reflection of a Line by Another Line

The reflection of the line 5x - 7y - 13 = 0 by the line y = -x is ....
A. 7x + 5y - 13 = 0
B. 7x + 5y + 13 = 0
C. 7x - 5y - 13 = 0
D. 7x - 5y + 13 = 0
E. 7y + 5x + 13 = 0

This one I totally have no idea. Like, at all.

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Bob

Administrator

Registered: 2010-06-20

Posts: 10,640

Re: [ASK] Reflection of a Line by Another Line

If you sketch the axes and the line of reflection you see that reflected points switch their x and y coordinates and reverse the signs eg (3,-4) becomes (4,-3)

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob