Question

Given that OA = 2x + 9y, OB = 4x + 8y and CD = 4x - 2y, explain the geometrical relationships between the straight lines AB and CD.

Answer 1

Answer:

The geometrical relationships between the straight lines AB and CD is that they have the same slope

Step-by-step explanation:

Given

$OA = 2x + 9y$

$OB = 4x + 8y$

$CD = 4x - 2y$

Required

The relationship between AB, CD

Since AB is a straight line and O is the origin, then:

$AB = (c - a)x + (d - b)y$

Where:

$OA = ax + by$ ====> $OA = 2x + 9y$

$OB = cx + dy$ ====> $OB = 4x + 8y$

This implies that:

$a =2$      $b = 9$     $c = 4$   $d = 8$  

So:

$AB = (c - a)x + (d - b)y$

$AB = (4 - 2)x + (8 - 9)y$

$AB = 2x -y$

So, we have:

$AB = 2x -y$

$CD = 4x - 2y$

Calculate the slope (m) of $AB\ and\ CD$

$m = \frac{Coefficient\ of\ y}{Coefficient\ of\ y}$

For AB

$m_1 = \frac{-1}{2}$

$m_1 = -\frac{1}{2}$

For CD

$m_2 = \frac{-2}{4}$

$m_2 = \frac{-1}{2}$

$m_2 = -\frac{1}{2}$

By comparison:

$m_1 = m_2 = -\frac{1}{2}$

This implies that both lines have the same slope