Question

parallel lines have the same______slope.
perpendicular lines have __________ (sign change) and __________ (\flip it\) slopes of each other.

note: if two lines are __________, then the product of their slope is __________.

slope bank
m = 2/4 - 140% + ?
1

Explanation:

Parallel lines have equal slopes. Perpendicular lines have opposite - sign (negative reciprocal) slopes. If two lines are perpendicular, the product of their slopes is - 1.

Answer:

Perpendicular lines have opposite - sign (sign change) AND reciprocal ("flip it") slopes of each other. If two lines are perpendicular, then the product of their slope is - 1.