The point (1;2) is on the line that is perpendicular to the line x+y-1=0. Determine the equation of the perpendicular line?

Expert Answers

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Given the point (1,2) is on the line.

Then we know that:

y-y1 = m(x-x1)

==> y -2 = m(x-1)

Now we need to find the slope m.

But we are given the equation of the line parallel to the equation.

x+y-1 = 0

We will rewrite into the slope form.

==> y= -x + 1

Then the slope is -1.

Since the lines are perpendicular, then the product of the slopes is -1.

==> -1 * m = -1

Then m = 1

==> y-2 = 1 (x-1)

==> y= x -1 + 2

==> y= x +1

==> x -y +1 = 0

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