If you do EVERY PROBLEM, GREAT!!
REQUIRED:
Do all problems 8-1 thru 8-4
Do 8-5 #1,3,5 only (no surface area of cones on test)
Do 8-6 #1-4, 7, 11
Do 8-7 #1-7 Odds
Do 8-8 #1-3
Please spread the work to your math-buddies that the assignment was reduced... thanks!
This question was asked earlier...
ReplyDeleteAnonymous said...
im confused on how to draw a net and I already watched the video tutors...
Answer:
In the case of a rectangular prism or square pyramid, a net is simply a drawing of the unfolded panels of the box.
The case of a cylinder is similar... instead of panels you can actually envision the "unfurling" of the cylinder wall. We have demonstrated this in class several times and in our lab the other day.
If you can ask a more specific question perhaps I can help you more.
is the surface area of cones going to be on the test?? rj
ReplyDeleterj doesnt understand 8-7 prob 7. i tried everything but i keep getting different answers. help now!!!!
ReplyDeleteHi mr, chamberlain I seem to be a little confused on lateral area?? I understand S.A and volume
ReplyDelete-sam
For RJ
ReplyDeleteYou just reverse the order of operations so dividing 88 by 8 and 4.6 to get the answer
PS: for the other problems do not forget pie.
Marc
to rj i got a very strange number on 8-7 #7 but it is just algebra I think 4.6(8)(x)=88
ReplyDeleteI multiplied and got 36.8 then divided that from 88 and got 2.391304348??
For problem 8-7 #7
ReplyDeleteI got 7.2m is that correct??
From the last comment how did you get that answer?
ReplyDeleteHow do you do the set-up the problem for 8-5 #7? I had the surface area of a cone is= pie (r2)= pie (r) (slant)
ReplyDeleteare you going to post an answer key...?!
ReplyDeletefor problem 8-7 #7 i got 2.4 (2.39)
ReplyDeleteis the sphere stuff going to be on the test
ReplyDeleteluke
Sphere stuff on the test... you will have the formulas... so, e-z-schmeezy, right?
ReplyDeleteLateral area is a very simple concept... From a geometric perspective, "lateral" is synonymous with "sidewall"... So the lateral area of a prism is the area of the sidewalls - you don't include area of the base or the top. For a pyramid or cone, it is the area of the sidewall and you don't include the area of the base (there is no top). Ca-peesh??
ReplyDeleteThe book gives you a description and formula on pg 375, but who needs a stinkin' formula when you understand and can construct it?
8-7 #7 was described pretty well above, but I'll give it another try as well.
ReplyDeleteYou are given the volume of a rectangular pyramid, with l=8m, w=4.6m, V=88m^3
We know the formula for Volume is V=(1/3)lwh, yes?
I'll demonstrate two options:
Option 1:
V=(1/3)lwh so, let's substitute what we know
88=(1/3)(8)(4.6)h let's multiply (simplify)
88=12.27h
h=88/12.27
h=7.17 (rounded)
Option 2:
An industrious algebra student might choose to create a formula for height from the original V=(1/3)lwh formula.
If you multiply both sides by 3 and divide by lw, you get h=3V/lw... what fun!
So, just substitute and solve...
h=3(88)/[(8)(4.6)]
h=264/36.8
h=7.17 (rounded)
I prefer option 2, but both methods work JUST FINE!
Ca-peesh??
are you posting the answer key??
ReplyDeleteNO SURFACE AREA OF CONES ON THE TEST, SO YOU CAN SKIP 8-5 #7,9, OK???
ReplyDeleteI WILL POST A PARTIAL ANSWER KEY... LET ME KNOW IF ANY PARTICULAR PROBLEM IS GIVING YOU TROUBLE.
ReplyDeletePractice 8-4
ReplyDelete#1) 2(5*8)=80 (front&back)
2(12*8)=192(right&left)
2(5*12)=120(top&base)
Surface Area (S.A.)= 80+192+120=392cm^2
#2) 2[1/2(6*8)]=48 (area of two triangles)
you'll need to use the Pythagorean theorem to find the length of the hypotenuse (which is 10m)
10*15=150 (side right panel)
8*15=120 (back left panel)
6*15=90 (base panel)
S.A.= 48+150+120+90=408m^2
#3) A cube!!!
6 faces, all 14*14
so, 6(14^2)=6(196)=1176in^2
#5) Area of base=Pi*r^2=3.14*(3.5)^2
=3.14*12.25=38.47in^2
Length of sidewall = Circumference of Circle
Circumference=Pi*d=3.14*7=21.98
Area of sidewall (L.A.)=lw=21.98*28=615.44in^2
S.A.=Twice the Base plus the L.A.
S.A.=2(38.47)+615.44=76.94+615.44=692.38in^2
Practice #8-5
ReplyDelete#1
Area of Base = 6^2 = 36cm^2
Area of Triangular Panel=(1/2)6*11=33cm^2
4 triangles= 4*33=132cm^2
S.A.=36+132=168cm^2
#3
Area of Base = 7.5^2 = 56.25in^2
Area of Triangular Panel=(1/2)7.5*10=37.5in^2
4 triangles= 4*37.5=150in^2
S.A.=56.25+150=206.25in^2
#5
Area of Base = 1.5^2 = 2.25cm^2
Area of Triangular Panel=(1/2)1.5*3.4=2.55cm^2
4 triangles= 4*2.55=10.2cm^2
S.A.=2.25+2.55=4.8cm^2
ahhhh mr. c for number 5... its the lateral area not the surface area i got 10.2 is it correct? evan
ReplyDelete#8-6
ReplyDelete#1
V=lwh
V=24*7*8=1344cm^3
#2
27*27*27=27^3=19,683in^3
#3
Two ways to look at this:
It is a triangular prism with a base area of (1/2)12*16=96yd^2 and 24 yards "high"
so, 96*24=2,304yd^3
OR
The triangular prism is HALF THE VOLUME of the rectangular prism that measures 12*16*24. It's volume would be 12*16*24=4608yd^3, and half of 4608=2,304yd^3.
A very nice cross-check!
#4 is a little tricky (not too bad). You need the Pythagorean theorem (again) to find the length of the missing side of the triangle. In this case a^2=c^2-b^2 or a^2=17^2-15^2
a^2=289-225
a^2=64
a=8
Now,
Area of one triangle is (1/2)8*15=60in^2
Let's call that the base.
The volume is the area of the base * the height
60*11=660in^3
8-6 #7
ReplyDeleteArea of the base=pi*r^2=3.14*7^2=3.14*49=153.86ft^2
Volume is Area of the base * height
153.86*42=6,462.12ft^3
i know 8-6 number 4 is really easy but i cant get it i just cant evan
ReplyDeleteFor 8-5 #5... Evan is correct... as you can see, since I showed my work(!!!!), I did specify that the area of the side panels was 10.2cm^2.
ReplyDeleteIs anyone else paying attention? Any problems?
I found a typo in 8-4 #5 you said that the diameter is 7 in even though on the problem that is the radius. There fore you put the radius as 3.5 not 7 in your work. :)
ReplyDelete- Sam Rollenhagen *cough* *cough* extra credit
For #8-7, you should do both a pyramid and a cone.
ReplyDelete#1
V=(1/3)lwh
V=(1/3)6*6*5
V=(1/3)180
V=60cm^3
#2
V=(1/3)(pi)(r^2)(h)
V=(1/3)(3.14)(7.4^2)(15.6)
V=(1/3)(3.14)(54.76)(15.6)
What I like to do here, instead of multiplying by .33, is to multiply the other numbers and divide by three. As you know, dividing by 3 is equivalent to multiplying by 1/3, and it is slightly more accurate than multiplying by .33 (you lose precision because of the repeating decimal).
V=[(3.14)(54.76)(15.6)]/3
V=2,682.36/3
V=894.12 m^3 (rounded)
anyone on 8-6 number 4 its a triangular prism why cant i do it evan
ReplyDeletePractice 8-4
ReplyDelete#1)
2(5*8)=80 (front&back)
2(12*8)=192(right&left)
2(5*12)=120(top&base)
Surface Area (S.A.)= 80+192+120=392cm^2
#2)
2[1/2(6*8)]=48 (area of two triangles)
you'll need to use the Pythagorean theorem to find the length of the hypotenuse (which is 10m)
10*15=150 (side right panel)
8*15=120 (back left panel)
6*15=90 (base panel)
S.A.= 48+150+120+90=408m^2
#3) A cube!!!
6 faces, all 14*14
so, 6(14^2)=6(196)=1176in^2
#5)
Area of base=Pi*r^2=3.14*(7)^2=3.14*49=153.86in^2
Length of sidewall = Circumference of Circle
Circumference=Pi*d=3.14*14=43.96
Area of sidewall (L.A.)=lw=43.96*28=1,230.88in^2
S.A.=Twice the Base plus the L.A.
S.A.=2(153.86)+1,230.88=307.72+1,230.88
S.A.=1,538.6in^2
Did I get it right, Sam?
Evan, did you see my explanation of 8-6 #4?
ReplyDeletejust did thanks
ReplyDeletewait nooooooo wrong one no wonder i was soooooooo off donde esta where is it
ReplyDelete^
ll
ll
ll where is it up there?
nevermind i am a genius and a big boy and i figured it out ALL BY MYSELF! small victory
ReplyDelete8-8
ReplyDelete#1
Circle with radius 10cm
S.A.=4(pi)r^2
=4(3.14)(10^2)
=1,256cm^2
V=(4/3)(pi)r^3
Hint: Multiplying by 4/3 is equivalent to multiply by 4 and then dividing by 3
So you could do this (more accurate):
V=[(4)(3.14)(10^3)]/3
V=[12,560/3]
V=4,186.66cm^3
OR this:
V=(1.33)(3.14)(10^3)
V=4,176.2cm^3
See how much difference 4/3 vs. 1.33 can make??
I will accept either method/solution on the test.
it's a good thing this blog is anonymous... i don't wanna know who "donde esta" is!!
ReplyDeletei aced that soooooo easy cuz im a big boy now and id did it ALL BY MYSELF small victory evan
ReplyDeletedonde esta means WHERE IS IT in SPANISH ERROR on comment number 34
ReplyDeletemr c 60x11 isnt 660 (in 8-6 #4) -amanda !
ReplyDeletecatch my mistake sam haha it is 660 whoops.
ReplyDeleteminus 10 pts for Amanda! is that ok with everyone?
ReplyDeleteyup
ReplyDelete8-5 #5 confuses me
ReplyDelete