GCSE Maths - Perpendicular Lines #75

The video tutorial explains the concept of perpendicular lines, highlighting that they intersect at 90 degrees. It describes how to verify perpendicularity by checking if the product of their gradients equals -1. The tutorial includes examples to illustrate this concept and demonstrates how to find the gradient of a perpendicular line using the formula m2 = -1/m1. It also touches on finding the equation of a perpendicular line when given a point it passes through.

What is a key characteristic of perpendicular lines?

• They never intersect.

• They intersect at 90 degrees.

• They have the same gradient.

• They are parallel.

If two lines have gradients m1 and m2, what is true if they are perpendicular?

• m1 / m2 = 1

• m1 * m2 = -1

• m1 - m2 = 0

• m1 + m2 = 1

Given two lines with gradients 1/2 and 3, are they perpendicular?

• No, because they are parallel.

• Yes, because they intersect at 90 degrees.

• No, because their product is not -1.

• Yes, because their product is -1.

How do you find the gradient of a line perpendicular to y = 1/3x + 3?

• Subtract 1 from the gradient, 2/3.

• Double the gradient, 2/3.

• Use the negative reciprocal, -3.

• Use the same gradient, 1/3.

What additional information is needed to find the equation of a perpendicular line?

• The x-intercept of the original line.

• A point through which the perpendicular line passes.

• The y-intercept of the original line.

• The length of the original line.