SOLUTION: let: L1: y=3 and L2: x=3 prove that:slop(L1) × slop(L2) =

SOLUTION: let: L1: y=3 and L2: x=3 prove that:slop(L1) × slop(L2) = - 1

Question 1139999: let: L1: y=3 and L2: x=3 prove that:slop(L1) × slop(L2) = - 1
Found 2 solutions by MathLover1, greenestamps:
Answer by MathLover1(20850) (Show Source): You can put this solution on YOUR website!

let:
:
:
prove that:

origin with these two points form right triangle which has legs , parallel to , with say horizontal and vertical
basic idea: if a right triangle has legs , parallel to axes, with say vertical, and you that right triangle by degrees counterclockwise, the new triangle will have vertical side and horizontal side .
Slope of first triangle's hypotenuse is .
Slope of new triangle's hypotenuse is .
Those hypotenuses are , because of the degree rotation, and the of their slopes is:

.....in your case ,

->proven

Answer by greenestamps(13200) (Show Source): You can put this solution on YOUR website!

The solution by tutor @MathLover1 did not address the conditions of the problem; and her answer is therefore very wrong.

The proposition is NOT true; the product of the slopes of L1 and L2 is NOT -1.

The slope of L1 is 0, and the slope of L2 is undefined. The product of "0" and "undefined" is not -1.

Two lines for which the product of the slopes is -1 are perpendicular.

However, the product of the slopes of two perpendicular lines is -1 ONLY IF THE TWO LINES ARE NOT ONE HORIZONTAL AND ONE VERTICAL.

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