Question

The figure below shows Dora’s semi-circular patio. The shaded region represents the tiled portion of the patio.

http://tinypic.com/r/5raz9/6

The width of the tiled portion is 1.5 feet. What is the area of the tiled portion of the patio, rounded to the nearest whole square foot?

14 square feet

20 square feet

40 square feet

44 square feet

Answer 1

calculate area of 'outer' semicircle ( = pi*r^2)

diameter 10 ft so radius = 5

'inner' area has diameter 10 - 2(1.5) ft so radius is 3.5 ft

then subtract

Answer 2

you need to find the areas of 2 semi circles...

\[A = \frac{1}{2} \pi r^2\]

the outer semi-circle has a diameter of 10 ft... so a radius of 5 ft

the inner semi-circle has a diameter of (10 - 2 x path width). Halve this answer for the radius.

the the area of the path is

Path Area = Area of Outer - Area of Inner.

Answer 3

Is it B?

Answer 4

have you don the calculations?