Four circles perfectly fit into one square. The shaded area is 16 (units squared). What is the area of the square?
ANSWERWe don't know the radius of the circles, so we just call it
r.
The WIDTH OF THE SQUARE (and height) is four times the radius of the circles, which is
4r.
AREA OF SQUARE = base ? height = 4r ? 4r =
16r?AREA OF EACH CIRCLE = PI ? r?
AREA OF SQUARE - AREA OF FOUR CIRCLES = SHADED AREA
16r? - PI ? r? = 16
This is where it gets difficult. We factorise for r?.
r?(16 - PI) = 16
Then we divide.
r? = 16 ? (16 - PI)
r? = 1.244
FINALLYAREA OF SQUARE = 16r? = 16 ? 1.244 =
19.91I have a twelve-year-old student who can do this.