Loading web-font TeX/Main/Regular

Saturday, August 20, 2022

2022/057) Given (a-5)^2 + (b-7)^2 = 4 find the minimum of (a+7)^2 + (b+2)^2

(a-5)^2 + (b-7)^2 = 4 is a circle whose centre is (5,7) and radius is 2

We need to find minimum of (a+7)^2 + (b+2)^2 that is distance of the point A with coordinates a,b  fom (-7,-2).

This is minimum when the point lies on the straight line from (-7,2) , (5,7) . 

this distane from (-7,2) to (5,7) = \sqrt{(5+7)^2 + (7-2)^2} = 13

the distance of a from (5,7) is 2

so distance of point from (-7,2)is 13 - 2 = 11

so minmum of  (a+7)^2 + (b+2)^2 is 121

  

No comments: