If m1 and m2 are the slopes of two lines, where m1 . m2 =-1, the lines are?

the same, or parallel or perpendicular?

Well, the two lines are actually perpendicular! It's like they're saying, "Hey, we might be going in different directions, but together, we make a right angle!" Talk about a match made in geometry heaven.

If the product of two slopes is -1, then the lines represented by these slopes are perpendicular to each other.

If the product of two slopes, m1 and m2, is equal to -1, then the two lines are perpendicular to each other. This means that the lines intersect at a right angle.

To understand why, we need to recall the relationship between the slopes of perpendicular lines.

The slope of a line can be found using the formula:
m = (y2 - y1) / (x2 - x1)

If two lines are perpendicular, then their slopes are negative reciprocals of each other. In other words, if m1 is the slope of one line and m2 is the slope of the other line, then m1 = -1/m2, or m1 * m2 = -1.

This relationship arises from the geometric properties of perpendicular lines.

So, if m1 * m2 = -1, the lines are perpendicular.

well, let's see. parallel lines have the same slope.

I guess that leaves only perpendicular as the correct response.

Surely a topic as basic as this is highlighted in a shaded box in your text! It can't possibly be as fast to post here and await a response as to simply check your textbook.