Homework Help v1.3

[Raug]

Ok, so I'm completely lost on my calculus homework...

The angle of elevation of the sun is decreasing at a rate of 0.25 rad/h. How fast is the shadow cast by a 400ft tall building increasing when the angle of elevation of the sun is pi/6.

Well, here's the picture I tried to use >.>




I think I have to find dx/dt if x is the length of the shadow. I was thinking that it's dx/dt = (arc?)tan 400/x But other than that I'm stuck

[Sharinganuser]

u guys are kinda nerdy ish lol i dont understand one word ur saying lol cept for mass

[Denny Crane]

d(theta)/dh= -.25
if theta is pi/6 (30 degress) and h= 400, then x (length of shadow)= 400/cos(pi/6)
which is 800. (forgive me if i'm wrong, but i'm doing this in my head)
now if x= 400/cos(theta)
= 400sec(theta)
cant remember more that that
let batgirl come and take the rest

[gaara of the desert]

Originally Posted by Zarael

Ok, so I'm completely lost on my calculus homework...

The angle of elevation of the sun is decreasing at a rate of 0.25 rad/h. How fast is the shadow cast by a 400ft tall building increasing when the angle of elevation of the sun is pi/6.

Well, here's the picture I tried to use >.>




I think I have to find dx/dt if x is the length of the shadow. I was thinking that it's dx/dt = (arc?)tan 400/x But other than that I'm stuck

I take it the sun is in the upper right corner of your picture, so the base of the figure is the length of the shadow.

at the moment:

tg(pi/6)= 400/length of shadow
tg (pi/6)= 0.577...
so length of shadow= 400/0.577...= 692.82m

in one hour:

tg (pi/6-0.25)= 0.28...
tg (pi/6-0.25)= 400/length of shadow
so length of shadow will be: 400/0.28...= 1425.33m


increase every hour is
400/tg((pi/6)-k*0.25) - 400/tg ((pi/6)- (k-1)*0.25)

whereas k is an amount of hours

[Denny Crane]

^i think you're meant to do it via calculus and want the instant rate of change

[gaara of the desert]

yeah, but it's not a linear function, I don't see how you could give the instant rate of change.

[Raug]

Well, I think it's like taking the dervivative and finding the equation for a tangent line anywhere on a curve.

Thanks though kaz and garra.

[AzNbOy123]

ok i need help on this one extra credit geometry question:
Prove why the ASS (angle-side-side) theorem doesnt work. It has to be logical and can't be: because its a bad word.
P.S Can use pictures to show.

[Denny Crane]

you mean the sides are not the ones involved in the angle?
cause that is the only way i can think it doesnt work

[Raug]

Gah, I did this exact same thing a few years ago. If I can find my notes (which I doubt) I'll try and get back to you >.>

[ViolinistBAKA]

Ahh...Need some help...and I need it within 12 hours, so I truly hope someone knowledgable comes by this.

for part of a Biology Essay

Compare and contrast Biotic and Abiotic factors in the ecosystem.

I am, for some reason, having an expressly difficult time doing this. T__T

[ViolinistBAKA]

*pyon!*

Notice me! TT__TT

[ames3]

Biotic are the living things such as bacteria, birds, trees, grass. Abiotic are the dead things such as water, air, soil..etc...i hope that helps=D

[Banana_Alchemist]

I need help once again,

Can anyone find me a pic of a nerve cell formation, thats easy to draw?

sort of like this one http://www.phantastic-art.com/medical/nerv.jpeg

If your wondering why i'm not using that one it's because i'm not really sure if its right cause the colour is different from what the textbook says

[Denny Crane]

what type of neuron do you want
there are a few different types, like how many projections come out of it?

basically you have a neuron cell body, with the smaller projections being the dendrites, which are usually are the receivers of the nerve impulse. then the axon which in some cases can be a metre long, extending from the opposite end. but as i said, it differs with the different types of neurons.

here is a simple diagram of a myelinated neuron (type A)
http://www.usm.maine.edu/psy/broida/101/neuron.JPG

[Jeaxz]

hey can someone help me on the global clitmate change: global warming like some good sites to link me

[Denny Crane]

what about it?
try looking up the kyoto protocol

but you need to be more specific about what point you want it on

[Jeaxz]

Originally Posted by kazman3

what about it?
try looking up the kyoto protocol

but you need to be more specific about what point you want it on

well yea im am kinda talking about the kyoto but i do not really get the kyoto thing u mind if u explain it or sumthing????? thanks

[Denny Crane]

the kyoto protocol is basically an agreement between nations which aims at reducing the amount of greenhouse gas emissions to target levels in an effort to battle global climate change. currently the only major countries not to sign the agreement is the US and Australia.

google it up and you will get a better explaination
this is way outside my feild of knowledge, maybe someone with good grounding in economics and politics can explain better

http://en.wikipedia.org/wiki/Kyoto_Protocol
there is the wikipedia info on it

http://www.google.com.au/search?clie...=Google+Search
there is the google search on it

[Jeaxz]

yo thanks a lot ill rep you