Question

8. K th 4. Use the formula S.A. = 2 X (IT X ) + (it xdxh) to calculate the surface area of each object. Give each answer to the nearest hundredth of d or to Example 1 on pages 59-61. a square unit. nets for this cylinder. 9. How could you simplify S.A. = 2 x (nt Xr2) + (st x d x h)? a) d= 2.5 cm rea to the nearest tenth 10 cm r= 10 cm b) d=5 cm b) 1 22 cm 7 cm ect to the

Answer 1

We are asked to calculate the surface area of the objects using the following formula

`SA=2*(\pi* r^2)+(\pi* d* h)`

Where r is the radius, d is the diameter, and h is the height of the circular cylinder.

Part a)

The diameter (d) is 2.5 cm

The height (h) is 10 cm

The radius is half of the diameter

`r=(d)/(2)=(2.5)/(2)=1.25\; cm`

Let us substitute the given values into the formula

`\begin{gathered} SA=2*(\pi* r^2)+(\pi* d* h) \\ SA=2*(\pi*1.25^2)+(\pi*2.5*10) \\ SA=2*1.5625\pi+25\pi \\ SA=3.125\pi+25\pi \\ SA=28.125\pi \\ SA=88.36\; cm^2 \end{gathered}`

The surface area of the object is 88.36 cm^2

Part b)

The diameter (d) is 5 cm

The height (h) is 7 cm

The radius is half of the diameter

`r=(d)/(2)=(5)/(2)=2.5\; cm`

Let us substitute the given values into the formula

`\begin{gathered} SA=2*(\pi* r^2)+(\pi* d* h) \\ SA=2*(\pi*2.5^2)+(\pi*5*7) \\ SA=2*(6.25\pi)+(35\pi) \\ SA=12.5\pi+35\pi \\ SA=47.5\pi \\ SA=149.23\; cm^2 \end{gathered}`

The surface area of the object is 149.23 cm^2