The circle shown below has a diameter of 18 centimeters. What is the
approximate area of the shaded sector?
A. 763 cm2
B. 509 cm2
C. 212 cm2
D. 191 cm2

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

use a calculator or a graph

the answers are

1. 2

2. 5

3. symmetrical