Find the image of the point (2,1) with respect to the line mirror `x+y-5=0`

Explanation

The point M lies on the line `x + y − 5 = 0`

` => a + b = 7 … (1)
`

Now, the lines` x + y − 5 = 0 `and AB are perpendicular.

Slope of AB × Slope of CD =− 1


`=> (b−1)/(a−2) xx (-1) = -1 `

` a – 2 = b – 1 ……(2) `
Adding eq (1) and eq `(2): 2a = 8 ⇒ a = 4 `
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