Areas of Polygons and Area Review help!

rogerwaters · 2013-11-02 00:37:50

Hi,

So I don't really get the concept of the lesson. If you guys could help me that'd be great!
I didn't put 18, 19, and 20 because there's a picture attached, if you guys could help me with these 17 first it'd love that. Thanks!

Calculate the area for each of the polygons below. If you do not know an equation to use, divide the polygon into other shapes to determine the area.

1. An equilateral triangle with a side of 1 inch
A 0.43 sq in
B 0.56 sq in
C 0.89 sq in
D 0.23 sq in
E 0.19 sq in
F 0.54 sq in

2. A square with a side of 2 feet
A 9 sq ft
B 4 sq ft
C 2 sq ft
D 7 sq ft
E 3 sq ft
F 8 sq ft

3. A regular pentagon with a side of 3 centimeters
A 23.01 sq cm
B 12.34 sq cm
C 39.17 sq cm
D 9.46 sq cm
E 34.21 sq cm
F 15.48 sq cm

4. A regular hexagon with a side of 10 cm
A 641.25 sq cm
B 194.45 sq cm
C 361.25 sq cm
D 259.81 sq cm
E 105.22 sq cm
F 453.01 sq cm

5. A regular heptagon with a side of 7 inches.
A 178.06 sq in
B 294.16 sq in
C 169.21 sq in
D 358.91 sq in
E 157.36 sq in
F 277.91 sq in

6. A trapezoid where the height is 18 cm, base 1 = 16 cm and b2 = 8 cm.
A 178.06 sq cm
B 122.5 sq cm
C 216 sq cm
D 230 sq cm
E 280.9 sq cm
F 510 sq cm

7. A trapezoid where the height = 7 mm, base 1 = 26 mm and base 2 = 9 mm.
A 178.06 sq mm
B 122.5 sq mm
C 216 sq mm
D 230 sq mm
E 28.9 mm
F 510 mm

Fill in the missing information for the following trapezoids:

8.
height = 19.8 cm
b1 = ________
b2 = 14.4 cm
area = 401.94 cm2

A 26.2 cm
B 12.5 cm
C 216 cm
D 23 cm
E 28.9 cm
F 51 cm

9.
height = 23 mm
b1 = 23 mm
b2 = ________
area = 529 mm2

A 78.06 sq mm
B 22.5 sq mm
C 21.6 mm
D 23 mm
E 28.9 mm
F 30 mm^2

10.
height = ________
b1 = 20 cm
b2 = 21 cm
area = 205 cm2

A 17.06 cm
B 12.5 sq cm
C 26 cm
D 10 cm
E 28.9 cm
F 50 cm^2

11.
height = 28.9 m
b1 = 26.9 m
b2 = ________
area = 806.31 m^2

A 17.06 sq m
B 15 m
C 46 m
D 23 m
E 28.9 m
F 51 m

12. If the area of a parallelogram is 690.84 m^2 and the height is 20.2 m, what is the length of the base?
A 78.06 m
B 22.5 m
C 216 m
D 34.2 m
E 28.9 m
F 51 m

13. If the base of a rectangle is 28 cm and the area is 588 cm^2, what is the height of the rectangle?

A 17.06 cm
B 122.5 sq cm
C 216 sq cm
D 23 cm
E 21 cm
F 51 cm^2

14. If the height of a rectangle is 26.1 m and the base is 17.3 m, what is the area of the rectangle?
A 451.53 m^2
B 122.5 m^2
C 216 m^2
D 430 m^2
E 289 m^2
F 510 m^2

15. If the height of a parallelogram is 34 cm and the base is 15 cm, what is the area of the parallelogram?
A 178.06 cm^2
B 122.5 cm^2
C 216 cm^2
D 230 cm^2
E 289 cm^2
F 510 cm^2

16. What is the area of a parallelogram with height 26 cm, base 16 cm, and side length 28 cm?
A 178.06 sq cm
B 122.5 sq cm
C 216 sq cm
D 416 cm^2
E 28.9 cm
F 510 cm^2

17. What is the area of a regular octagon with a side of 6 cm?
A 178.06 sq cm
B 122.5 sq cm
C 216 sq cm
D 23 cm^2
E 173.82 cm^2
F 510 cm^2

bobbym · 2013-11-02 01:50:19

1) A

2) B

3) F

4) D

5) A

Okay, I gave you a nice start. What do you think is the answer for 6?

rogerwaters · 2013-11-02 02:02:30

Thanks for the answers! But I don't know what formula or what technique I have to use, if you could tell me it. I would figure them out by myself.
Thanks!

bobbym · 2013-11-02 02:08:10

How is that? Can you now do a few or do you need help?

rogerwaters · 2013-11-02 02:11:50

I think I'm gonna need some help. From where do I get b1, b2 and the height. All they give me is the length of the side.
Mathew,

bobbym · 2013-11-02 02:15:30

6. A trapezoid where the height is 18 cm, base 1 = 16 cm and b2 = 8 cm.
A 178.06 sq cm
B 122.5 sq cm
C 216 sq cm
D 230 sq cm
E 280.9 sq cm
F 510 sq cm

They gave you base 1 and base 2.

rogerwaters · 2013-11-02 23:04:17

Okay so I have to do

6. a= (b1 * b2 * h)/2
a = (16 * 8 * 18)/2
a = 2304/2
a = 1152

I used the formula, but it doesn't match any of the answers. What did I do wrong
Mathew,

bobbym · 2013-11-02 23:14:43

Hi;

You did it right, I made a mistake on the formula, it is supposed to be:

The answer is C) 216. Sorry for the mistake. I have cleaned up the formula in the other post.

rogerwaters · 2013-11-02 23:23:02

No problem!
Okay so number 7 is:

7. A trapezoid where the height = 7 mm, base 1 = 26 mm and base 2 = 9 mm.

A 178.06 sq mm
B 122.5 sq mm
C 216 sq mm
D 230 sq mm
E 28.9 mm
F 510 mm

a = {(26 + 9) * 7} / 2
a = 122.5 mm

My answer is B

Right?
Mathew

rogerwaters · 2013-11-02 23:24:26

How can I do 8-11?
What method, or formula should I use?

bobbym · 2013-11-02 23:28:58

7 is correct.

8 - 11 you just plug in and solve for the missing term.

rogerwaters · 2013-11-02 23:43:16

Okay for number 8:

8.
height = 19.8 cm
b1 = ________
b2 = 14.4 cm
area = 401.94 cm2

A 26.2 cm
B 12.5 cm
C 216 cm
D 23 cm
E 28.9 cm
F 51 cm

A is the correct answer.

9.
height = 23 mm
b1 = 23 mm
b2 = ________
area = 529 mm2

A 78.06 sq mm
B 22.5 sq mm
C 21.6 mm
D 23 mm
E 28.9 mm
F 30 mm^2

Correct answer is 23 (D)

10.
height = ________
b1 = 20 cm
b2 = 21 cm
area = 205 cm2

A 17.06 cm
B 12.5 sq cm
C 26 cm
D 10 cm
E 28.9 cm
F 50 cm^2

the answer is 10 (D)

11.
height = 28.9 m
b1 = 26.9 m
b2 = ________
area = 806.31 m^2

A 17.06 sq m
B 15 m
C 46 m
D 23 m
E 28.9 m
F 51 m

The answer is 28.9 (E)

Mathew,

rogerwaters · 2013-11-02 23:46:21

Could you start helping me on the rest?
Thanks!

bobbym · 2013-11-02 23:50:49

Hi;

Hold on, while I check your answers.

8 to 11 are correct.

What help do you need with the rest?

rogerwaters · 2013-11-03 00:12:46

How do I do this one?

12. If the area of a parallelogram is 690.84 m^2 and the height is 20.2 m, what is the length of the base?
A 78.06 m
B 22.5 m
C 216 m
D 34.2 m
E 28.9 m
F 51 m

bobbym · 2013-11-03 00:16:09

The area of a parallelogram is:

A = b * h

can you do that one now?

rogerwaters · 2013-11-03 00:20:46

Okay so if A = b * h
then b= A/h
Right?

Then b = 690.84 / 20.2
=34.2 (D)
I got it!

Now what about #13 and #14. What is the formula for the rectangle

13. If the base of a rectangle is 28 cm and the area is 588 cm^2, what is the height of the rectangle?

A 17.06 cm
B 122.5 sq cm
C 216 sq cm
D 23 cm
E 21 cm
F 51 cm^2

14. If the height of a rectangle is 26.1 m and the base is 17.3 m, what is the area of the rectangle?
A 451.53 m^2
B 122.5 m^2
C 216 m^2
D 430 m^2
E 289 m^2
F 510 m^2

bobbym · 2013-11-03 00:28:25

34.2 is correct, A = b * h for a rectangle too, which is a type of parallelogram

rogerwaters · 2013-11-03 00:33:07

13. If the base of a rectangle is 28 cm and the area is 588 cm^2, what is the height of the rectangle?

A 17.06 cm
B 122.5 sq cm
C 216 sq cm
D 23 cm
E 21 cm
F 51 cm^2

THe answer is 21 (E)

14. If the height of a rectangle is 26.1 m and the base is 17.3 m, what is the area of the rectangle?
A 451.53 m^2
B 122.5 m^2
C 216 m^2
D 430 m^2
E 289 m^2
F 510 m^2

The answer is 451.53 (A)

15. If the height of a parallelogram is 34 cm and the base is 15 cm, what is the area of the parallelogram?
A 178.06 cm^2
B 122.5 cm^2
C 216 cm^2
D 230 cm^2
E 289 cm^2
F 510 cm^2

The answer is 510 (F)

16. What is the area of a parallelogram with height 26 cm, base 16 cm, and side length 28 cm?
A 178.06 sq cm
B 122.5 sq cm
C 216 sq cm
D 416 cm^2
E 28.9 cm
F 510 cm^2

Answer is 416cm^2 (D)

bobbym · 2013-11-03 00:36:27

That is what I am getting, very good!

rogerwaters · 2013-11-03 00:37:33

Alright thank you so much for your help! I'll send them and see what I got.

bobbym · 2013-11-03 00:39:50

Okay, let me know how you did.

rogerwaters · 2013-11-03 00:49:13

I sent them in and got 20/20 (I figured 17, 18, 19 and 20 by myself)
THANK YOU SO MUCH bobbym

rogerwaters · 2013-11-03 00:52:20

I also need some help with the next lesson, I'll send you the questions after I have lunch
Mathew,

bobbym · 2013-11-03 00:56:17

That is very good, I am going to take a break see you later with the questions.

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Areas of Polygons and Area Review help!

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