Parallel and Perpendicular Lines

Front

What are parallel lines?

Back

Parallel lines are lines in a plane that never meet or intersect, no matter how far they are extended. They have the same slope.

Front

What are perpendicular lines?

Back

Perpendicular lines are lines that intersect at a right angle (90 degrees). Their slopes are negative reciprocals of each other.

Front

What is the slope of a line?

Back

The slope of a line is a measure of its steepness, usually represented as 'm' in the equation of a line (y = mx + b).

Front

If two lines have slopes m1 and m2, when are they parallel?

Back

Two lines are parallel if their slopes are equal (m1 = m2).

Front

If two lines have slopes m1 and m2, when are they perpendicular?

Back

Two lines are perpendicular if the product of their slopes is -1 (m1 * m2 = -1).

Front

What is the slope of a line perpendicular to a line with slope 3?

Back

The slope of a line perpendicular to a line with slope 3 is -1/3.

Front

What is the slope of a line perpendicular to a line with slope -2?

Back

The slope of a line perpendicular to a line with slope -2 is 1/2.

Front

What are opposite reciprocals?

Back

Opposite reciprocals are two numbers whose product is -1. For example, if one number is 4, its opposite reciprocal is -1/4.

Front

Write the equation of a line with slope 2 that passes through the point (1, 3).

Back

y - 3 = 2(x - 1).

Front

Write the equation of a line with slope -1/2 that passes through the point (4, 2).

Back

y - 2 = -1/2(x - 4).