Region test questions

[bradp]

07H-38
I set up a system using the projectile motion equations for maximum horizontal distance (60.8 ft) and maximum vertical distance (12 ft)
and got x = arctan(2*12/60.8) = 21.5 deg which isnt right?

07H-60
got tan x = 1/ (tan (90-x)) and then i realized that that statement is true for any angle and since it doesn't really have any specific parameters of the problem it can't be the solution. hints?

[Kurt]

For 07H-38, it's helpful to know [unparseable or potentially dangerous latex formula], for h = max height, r = range.

Hints for #60: I used the fact that there is a chord there, and a tangent....after a chord formula and a trigonometric ratio, the answer pops out.

As a sidenote, I think that's the first problem on the calculator test I've ever seen that didn't have a single number in the problem, lol.

[stupidityismygam]

38) it is arctan(4v/h)

[bradp]

[unparseable or potentially dangerous latex formula]

radius cancels...
leaving

[unparseable or potentially dangerous latex formula]

that looks hot^

[wigianto]

can someone explain to me how to do the latitude/longitude problems?
ex. 07H-28
i don't have a clue so i always have to skip them...
and 07H-35 my calculator overflows but someone told me you're supposed to use log.. help please?

[Celsion]

Let's see: 07H-36
What is [unparseable or potentially dangerous latex formula]?

Set [unparseable or potentially dangerous latex formula]
Now log both sides: [unparseable or potentially dangerous latex formula]
Using one of the properties of log, carry down [unparseable or potentially dangerous latex formula].
[unparseable or potentially dangerous latex formula]
Solve the right side of the equation and write it out.
[unparseable or potentially dangerous latex formula]
Now raise each side to the power of 10.
[unparseable or potentially dangerous latex formula]
The left side simplifies back to y. The right you can break down using an exponential rule.
[unparseable or potentially dangerous latex formula]
So now solve out [unparseable or potentially dangerous latex formula].
[unparseable or potentially dangerous latex formula]

[bradp]

This is actually a study list problem.. i was surprised to see it @ #28

If you draw a circle representing the earth, you can find the radius of a horizontal circle which has a constant latitude
It comes out to:

[unparseable or potentially dangerous latex formula] and R = 3960 mi.

the circumference of the earth at the constant latitude is

[unparseable or potentially dangerous latex formula]

from 37 deg 36' E to 12 deg 34' E is only a fraction of the full circumference though.. so

[unparseable or potentially dangerous latex formula]

and convert to km..

[wigianto]

ohh i see thanks,
so i figure if you don't get a constant latitude, you'd do something similar to distance formula for rectangular coordinates and divide that by 360 and multiply circumfrence?

[bradp]

I don't know much (anything) about spherical geometry, but there's probably a way to do it with that. I wouldn't worry about it showing up on a calculator test.

[Celsion]

How many crunchers did everyone miss on the regional test? I missed 8.

[wigianto]

i missed 4 but i use an 83 =)
and consequently didn't answer as many stated or geometry to get a medal =(

[Kurt]

I missed 3.

To my knowledge, they've never had a problem where the cities were on different latitudes AND longitudes...

However, if they did, I'd probably transform the axes such that one pair ARE the same, and use appropriate angles to revolve the other ones (and then work it out normally).

As a tip, if you use an HP-33s, you can quickly go from degree/minute/second to a decimal format by using the ->HR button. The format is degrees.MNSC (two decimal places afterward for the minute, and the next two for the second).

Although typing in the /60 part I guess doesn't really take THAT much more time... :P

[bradp]

I took a molasses-esque (relative to my district time) 10:30 to finish the crunchers for some reason.. missed 2. It didn't matter in the end, though, because I spent the last 2 minutes looking for a problem to do but I didn't (at the time) know how to do any..

I missed 2 crunchers, 2 study listers, and a page 2 word problem and I skipped 7. Shouldn't have missed those -_-. I hope the state test isn't too hard.

[Celsion]

I'm mad, I made so many stupid mistakes on calculator and answered enough for a 276. I forgot to convert like 2 stated, such as the rug, and the highest and lowest point on earth. Missed the surface area of the sphere, the first scalene triangle, the truncated cube. I even missed the matrix one, I though it was column, row, not row, column.

[Kurt]

[PatriotAlanis]

Did anyone do the inverted cone problem... we did it today and none of my students (nor I) agree with the given answer. We think it's unreasonable. If anyone can explain how to get the answer given, it would be appreciated.

[bradp]

Did you find the volume of the cone or just the height?
The height is [unparseable or potentially dangerous latex formula] and the volume formula works out to give exactly 10 times that, [unparseable or potentially dangerous latex formula]

18 inches tall... 6 in. radius so

[unparseable or potentially dangerous latex formula]

[unparseable or potentially dangerous latex formula]

[unparseable or potentially dangerous latex formula]
[unparseable or potentially dangerous latex formula]

solve: [unparseable or potentially dangerous latex formula]

putting into volume equation:[unparseable or potentially dangerous latex formula]


i pwn @ latex

[ZachB]

I've corrected all my mistakes on the calculator test except for 07H-60. Could someone please explain to me in simpleton terms the formulas needed to solve it and how to use them?

[Kurt]

[ZachB]

Wow, thank you. It seems so simple now, I almost feel like an idiot for asking. The only part I was missing using that chord formula and watching as the radius cancelled. Maybe there will actually be some numbers on problems 59 and 60 at state...