Parallel and Perpendicular Lines

Front

What are parallel lines?

Back

Parallel lines are lines in a plane that never meet. They have the same slope but different y-intercepts.

Front

What are 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

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

Back

Two lines are parallel if m1 = m2.

Front

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

Back

Two lines are perpendicular if m1 * m2 = -1.

Front

Write the equation of a line parallel to y = 2x + 3 that passes through (1, 4).

Back

y = 2x + 2.

Front

Write the equation of a line perpendicular to y = -1/3x + 5 that passes through (3, 2).

Back

y = 3x - 7.

Front

What is the slope of the line y = 4x + 1?

Back

The slope is 4.

Front

What is the slope of the line y = -2x + 3?

Back

The slope is -2.

Front

Are the lines y = 5x + 1 and y = 5x - 3 parallel?

Back

YES, they are parallel because they have the same slope.

Front

Are the lines y = 2x + 1 and y = -1/2x + 4 perpendicular?

Back

YES, they are perpendicular because their slopes (2 and -1/2) are negative reciprocals.