An engineer decides to use similar triangles to find the distance across the river. She makes the diagram below.

a. Which triangles appear to be similar? What must the
engincer know about these triangles to conclude that
they are similar?

B. Find the distance across the river from point B to point A.

C. Why does BC have the same slope as CD

tip $2.90

total $17.40

hello from mrbilldoesmath!

answer:

(7 x + 6 y) (49 x^2 - 42 x y + 36 y^2)

discussion:

the trick is to recognize that 343 = 7^3 and 216 = 6^3 and, in general,

a^3 + b^3 =   (a + b) (a^2 - a b + b^2).

in our case

343x^3+216y^3   =   (7x)^3 + (6y)^3

so take a = 7x and b = 6y in the above equation to get the answer.

you,

mrb

english maybe i can ..