Question

will someone please help me with these 9 problems that i have already did and got wrong... Please help

Answer 1

these two i had to find the base area... and i got them wrong

Answer 2

What are the shapes of bases on each picture? What are the formulas to calculate areas of these figures?

Answer 3

traingle and a circle

Answer 4

Correct. What kind of triangle? It's a *regular* pyramid.

Answer 5

equallaterial

Answer 6

Yup. So you have to find an area of a circle given it's radius and an area of an equilateral triangle given the length of this side. Both formulas can be found easily, e.g. on wikipedia.

If you want an additional challenge you can devise the formula for triangle using the Pythagorean theorem (if you draw its height you'll get a right triangle).

Answer 7

for the triangle wouldnt it be 1/2*4*4=8cm

Answer 8

Nope, its height does not equal 4.

Answer 9

what is the height

Answer 10

"Altitude" is another word. http://en.wikipedia.org/wiki/Altitude_%28triangle%29

I assume you used the formula for triangle that's given as area = 1/2 * base * height.

Answer 11

yea...
for the cone the base area would be 113.0976 or 113.1in

Answer 12

\[113.1 in^{2} \]

That is square inches. Correct.

Answer 13

i still dont know how to find the base area of the pyramid

Answer 14

Area of base: ½b×h

Answer 15

1/24*7=14cm

Answer 16

1/2*4*7=14cm

Answer 17

The wikipedia page about equilateral triangles has the formula that uses only the side length.

Answer 18

1/2*4*7=14cm so this isnt right

Answer 19

No, it's not right.

Answer 20

i give up

Answer 21

Too early. You're given an equilateral triangle with side length of 4cm. Apply the formula from: http://en.wikipedia.org/wiki/Equilateral_triangle

Answer 22

A=\frac{\sqrt{3}}{4} a^2

Answer 23

Yes, this one.

Answer 24

6.93

Answer 25

Correct!

Answer 26

okay.. how are these two wrong.. finding the volume

Answer 27

In both cases you got the base area wrong. First case is the same as the problem you've just solved. Second one has a base that can be thought of as consisting of multiple triangles.

Answer 28

the first one the base area would be 10.83

Answer 29

Indeed.

Answer 30

so the volume would be 32.49in cubed

Answer 31

True.

Answer 32

what formula would i use to get the base area for the hexagon

Answer 33

It consists of six equilateral triangles.

Answer 34

\[\sqrt{6}\div4\times3^{3}\]

Answer 35

\[3^{3}?\]

Answer 36

7^3

Answer 37

Let's do it more slowly. What's the area of one of the triangles that form that hexagon?

Answer 38

\[\sqrt{3}\div4\times7^{3}\]

Answer 39

7^2

Answer 40

Yes. And there's six of them. So the area of the whole hexagon is..?

Answer 41

21.21*5

Answer 42

5?

Answer 43

21.22*6

Answer 44

Much better. You can get the correct volume now.

Answer 45

127.31

Answer 46

Looks good to me.

Answer 47

381.92 would be the volume?

Answer 48

No, you must have missed something in the formula for volume.

Answer 49

127.31 this is the area of one side base or all

Answer 50

There's only one base in this case.

Answer 51

127.31 is the base area right

Answer 52

Yes.

Answer 53

than to get the volume dont i * by 3

Answer 54

You do, but there's a division there too.

Answer 55

190.97

Answer 56

Pyramid (1/3) * (base area) * height

Answer 57

That's the correct formula, yes. Height is 3cm if I read the picture correctly.

Answer 58

yeah

Answer 59

(1/3) * 3 * 127.31 = ..?

Answer 60

190.97cm^3

Answer 61

127.32 * 3 / 3 = ..?

Answer 62

127.32

Answer 63

Aye.

Answer 64

(127.32 * 3) / 3 = 127.32

Answer 65

Multiply by the numerator, divide by denominator. That's how you multiply a number by fraction. Surprisingly 127.32 cubic centimeters is the answer. It's the same number as the base area, but unit differs (cubed vs squared).