No.15 (b)

Twila made the object shown.

Length = 12 cm

Width = 3 cm

Height = 8 cm (For those who are having troubles seeing the measurements)

#1 : Find the area of each face(Because i know that the front/ back, sides, and top/bottom are asymmetrical, what I'm going to do is solve for one face and multiply it by two, to find the other.

Top and bottom :

3 x 12 x 2 = 72 cm

^{2}

Sides :

8 x 3 x 2 = 48 cm

^{2}

Front and back :

8 x 12 x 2 = 192 cm

^{2}

#2 : Once the area of all faces has been solved, you add them all together to find the surface area of the whole figure (without the hole in the middle)

72cm

^{2}+48cm

^{2}+192cm

^{2}=312cm

^{2}

#3 : Find the area of the hole in the middle of the figure. To do that use the formula of a cylinder.

2 x π x r

^{2}+ 2 x π x r x h =

First solve the first part of the formula -

2 x π x 2

^{2}= 25.12

Next solve the second part of the formula -

2 x π x 2 x 3 = 37.68

Then add those two, to solve for the final answer of the formula

37.68 + 25.12 =62.80

#4 : Add the area of the hole to the area of all the faces to find the total surface area of the whole figure including hole in the middle.

62.80+312 = 374.8cm

^{2}

#5 : Last but not the least subtract the two ends of the hole from the surface area to get the final answer.

374.8- 25.12= 349.68cm

^{2}

There is my scribe post for number 15. Remember that there were mistakes from the way i solved for the answer, so please make corrections so that when other people reads this they will get the right answer, it also helps me too! Anyways, i hope my scribe wasn't hard to understand. And DO YOUR HOMEWORK GUYS !

Its "the front/ back, sides, and top/bottom are SYMMETRICAL."

ReplyDeleteAnd I think it should be (surface area of rectangular prism) + (2πrh) - (2πrsquared).

Oh yeah , typo. . sorry. And thanks :)

ReplyDeleteAnd you don't add 62.80(SA of cylinder) to 312(SA of rectangular prism). You add the 37.70(Area of the rectangle for the cylinder) to the 312, then subtract the 2 circles.

ReplyDelete