Find the slope of the line passing through each of the following pairs of points. (−3, 9), (−3, −5) (5, 6), (3, 4) (0, 7), (0, −8) (4, 0), (−2, 8)

Look carefully at the first pair:  (−3, 9), (−3, −5)  Note that x does not change, tho' y does.  This is how we recognize a vertical line (whose slope is undefined).  The equation of this vertical line is x = -3.

Looking at the second pair:  from (3,4) to (5,6), x increases by 2 and y by 2; thus, the slope is m = rise/run = 2/2 = 1.

Third pair:  as was the case with the first pair, x does not change here, and thus the equation of this (vertical) line is x=0 (which is the y-axis).  The slope is undefined.

part a: triangles gcb and epb

part b. sides cg and rp are parallel by definition of parallelogram.

angles cgb and e are congruent by being alternate interior angles of parallel lines cut by a transversal. angles gbc and ebp are congruent because they are vertical angles. by aa similarity, the triangles are similar.

part c. since the triangles are similar, the ratios of the lengths of corresponding sides are equal.

calculation of be:

gb/be = cb/bp

(400 ft)/be = 300/200

(400 ft)/be = 3/2

3be = 2 * 400 ft

3be = 800 ft

be = 800/3 ft

calculation of pe:

gc/pe = cb/bp

(350 ft)/pe = 300/200

(350 ft)/pe = 3/2

3pe = 2 * 350 ft

3pe = 700 ft

pe = 700/3 ft