There are two conclusions when linear equations are perpendicular to each other. One is K1 * K2 = - 1. What is the other?

There are two conclusions when linear equations are perpendicular to each other. One is K1 * K2 = - 1. What is the other?

There are two conclusions when the linear equations are perpendicular to each other, one is K1 * K2 = - 1, the other is K1 = 0, K2 does not exist or K1 does not exist, K2 = 0
That is, one line is parallel or coincident with the X axis (k = 0) and the other line is parallel or coincident with the Y axis (K does not exist)

Two straight lines of a function are perpendicular to each other, K1 * K2 = - 1. How to prove this theorem

It is proved by the direction of a straight line
Vector a = (1, K1)
Vector b = (1, K2)
Because the lines are perpendicular to each other, so (1, K1) (1, K2) = 0
1+k1k2=0
k1k2= -1

Why are two lines perpendicular to each other K1 * K2 - 1 in the plane rectangular coordinate system

Take a special case, y = x and y = - X are perpendicular, 1 * - 1 = - 1

The sum is as follows: A2 = B1 + C1 + D1 + E1; B2 / C2 / D2 is null or 0; E2 = G1 + H1 + I2 + J1 + K1; F2 / G2 / H2 is null or 0
E 2 = g 1 + H 1 + I 2 + j 1, cycle sum 4 columns

The formula for A2 is as follows:
=IF(MOD(COLUMN()-1,4)=0,B1+C1+D1+E1,"")
Then pull to the right