Determine the perimeter and area of the red portion of the 2 dimensional figure below, given the circle diameter of 7 cm and the perimeter of the entire figure is 42 cm. Round if necessary

Perimeter = 20cm ; area = 59.5cm

Step-by-step explanation:

Given the following :

Perimeter of entire figure = 42cm

Diameter of circle (d) = 7cm

Find the perimeter of the circle :

The perimeter (p) of a circle equals :

2πr

Where r = radius of circle

r = diameter /2 = 7/2 = 3.5cm

Therefore,

P = 2 * (22/7) * 3.5

P = 22 cm

Looking at the figure, we only take the semicircle :

Therefore perimeter of each semicircle =

22cm / 2 = 11cm

Therefore, perimeter of the red shaded region =

(42 - 22)cm = 20cm

Area of Circle = πr^2

(22/7) * 3.5^2 = 38.5 cm

Area of each semicircle = 38.5/2 = 19.25cm

Total area of semicircle = (19.25 +19.25) = 38.50cm

To find sides of rectangle :

Perimeter of the rectangle :

width = diameter of circle = 7cm

2(l + w) = 42

2(l + 7) = 42

2l + 14 = 42

2l = 42 - 14

2l = 28

l = 28/2

length (l) = 14cm

Therefore, area of rectangle :

Length * width

14 * 7 = 98cm

Area of red portion:

Area of rectangle - (area of the 2 semicircles)

98cm - 38.50cm

= 59.50cm