Parallel and Perpendicular Lines

Front

What is the definition of parallel lines?

Back

Parallel lines are lines in a plane that never meet. They are always the same distance apart and have the same slope.

Front

What is the definition of perpendicular lines?

Back

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

Front

How do you find the slope of a line given two points (x1, y1) and (x2, y2)?

Back

The slope (m) is calculated using the formula: m = (y2 - y1) / (x2 - x1).

Front

What is the slope of a horizontal line?

Back

The slope of a horizontal line is 0.

Front

What is the slope of a vertical line?

Back

The slope of a vertical line is undefined.

Front

Write the point-slope form of a line given a point (x1, y1) and slope m.

Back

The point-slope form is: y - y1 = m(x - x1).

Front

What is the equation of a line parallel to the x-axis that passes through the point (a, b)?

Back

The equation is: y = b.

Front

What is the equation of a line parallel to the y-axis that passes through the point (a, b)?

Back

The equation is: x = a.

Front

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

Back

They are perpendicular if m1 * m2 = -1.

Front

What is the domain of a function represented by a horizontal line?

Back

The domain is all real numbers, (-∞, ∞).