Is the line through points P(0, –9) and Q(2, –8) perpendicular to the line through points R(1, 4) and S(3, 3)? Explain.

Yes; their slopes are equal.
Yes; their slopes have product –1.
No; their slopes are not reciprocals.
Yes; their slopes have product –1.

Question

Is the line through points P(0, –9) and Q(2, –8) perpendicular to the line through points R(1, 4) and S(3, 3)? Explain.

Yes; their slopes are equal.
    Yes; their slopes have product –1.
    No; their slopes are not reciprocals.
    Yes; their slopes have product –1.

anonymous · Answer

The formula for slope is $$slope = (y_2-y_1)/(x_2-x_1)$$
so the slope of PQ is:$$(-8-(-9))/(2-0) = 1/2$$
The slope of RS is :
$$(3-4)/(3-1) = -1/2$$
In order for two slopes to be perpendicular, their product must be -1
(1/2)(-1/2) = -1/4 which isnt -1, so the lines arent perpendicular.
Answer is C