# Define a triangle with least perimeter having a fixed vertex (a,b) and other verices at X axis and line y=x(variable). How can i solve it using properties of optics?

Grade:12

## 1 Answers

Badiuddin askIITians.ismu Expert
148 Points
14 years ago

Dear twesh

point c should be selected such that reflection of point B on line y=x ,and point C and point A must be in straight line.(because straight line give shortest distance)

let the reflection of point B is D(0,X)

but again Ac+Bc =AD will be minimum when line AD will be perpendicular to y Axis

so D=(0,b)

and B (b,0)

so pint C become (b,b)

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