# Posts by Steve

Total # Posts: 52,287

**calculus**

well, you have tanz = r^2 tan2? z = arctan(r^2 tan2?) ?z/?r = (2r tan2?)/((r^2 tan2?)^2+1) ?z/?? = (2r^2 sec^2(2?))/((r^2 tan2?)^2+1) the second partials get a bit messy, but you can get them here: http://www.wolframalpha.com/input/?i=d%5E2%2Fdr%5E2+arctan(r%5E2+tan2%CE%B8) ...

**calculus**

just crank it out ?u/?x = 2x/(x^2+y^2) ?u/?y = 2y/(x^2+y^2 ?v/?x = -2y/(x^2+y^2) ?v/?y = 2x/(x^2+y^2

**MATH**

the link is missing a domain name, such as http://pictures.com/...

**math**

16 2/3% = 1/6 1/6 * 9 = ...

**math**

12* 5/3 = 5 * 12/3 = ...

**maths**

see your previous posts and work this the same way. We can check your answer.

**maths**

see your previous two posts and work this the same way. We can check your answer.

**maths**

this is the same as cos30/sin30 + sin30*cot30 = cot30(1+sin30) = ?3 (1+1/2) = 3?3/2

**maths**

These are standard angles, whose functions you would do well to learn Cos45+sin60-tan30 = 1/?2 + ?3/2 - 1/?3 = (3?2 + ?3)/6

**maths**

well, (1+cot²x) = csc²x

**Geometry**

there are many possible line segments drawn from a to bc

**Maths**

301 They all leave remainder

**Algebra**

what's the trouble? They say S = ?(30fL) just plug in your numbers and solve for L

**Algebra**

If the painting has length x and height y, and the frame has width w, then we have x+2w = 10 y+2w = 8 x^2+y^2 = 100 Now just solve for w

**Math**

I get 104. What do you get?

**Math**

try using <= for "less than or equal" "under 12" means "less than 12" so, what do you think?

**Math**

n > 130-87

**Math Check! #3**

yeah, but how does that relate to choosing 4 players from a group of 8?

**Math Check! #3**

Hmmm. How did you get 336? This is just a "choose 4 of 8" combination. 336 = P(8,3) How does that relate to this problem. I suspect you just guessed.

**maths**

not sure what -< and +< mean

**Math**

2/(3/4) = x/30

**Algebra2**

Thank you

**Algebra2**

The water level varies from 12 inches at low tide to 52 inches at high tide. Low tide occurs at 9:15 am. High tide occurs at 3:30 pm. What is a cosine function that models the variation in inches above and below the water level as a function of time and hours since 9:15 am? ...

**Geometry**

correct

**Algebra2**

The function f(theta) and g (theta) are sine functions where f(0)=g(0)=0. The amplitude of f (theta) is twice the amplitude of g(theta). The period of f(theta) is one-half the period of g(theta). If g (theta) has a period of 2pi and fpi/4=4. Write the function rule for g(theta...

**MATH**

since you give no indications of any side lengths, it's kinda hard for us to say, right? and besides, area is in cm^2, dontcha know

**Algebra2**

thank you

**Algebra2**

for which value of theta is tan theta equal to sin theta? My answer is pi

**math**

42.75*1.18

**Math**

if you mean the angle is 20°, then the radius r of the circle can be found using' 5/r = sin10° Now you know r, so you can find the area of the circle...

**chemistry**

how many moles in 5.3g? Molarity is moles/liter

**Math**

since xy=48 for each pair, B is correct.

**Algebra2**

Thank you

**Algebra2**

cos?+1 = 0 cot(?/2) = 0

**Algebra2**

Write three trigonometric equations each with the complete solution pi+2pin

**Physics-Circuits**

google is your friend

**Math**

180 degrees surely your geometry text proved that most basic fact of triangles!

**Math**

depends on your clock. Some keep 24-hour time. and who says "army" time isn't real? It's just not "civilian" time feet are just as real as meters -- it just depends on your yardstick ...

**HELP**

probably for the same reason you wasted our time posting the same stupid question again ...

**science**

ummm ... because they grow on cherry trees? Or maybe because cherries happen where those blossoms are. Or maybe because they've never been pollinated ...

**physics**

a) how long does it take to fall 132m? If it takes t seconds, b) the kit lands 68.9t meters away from where it was dropped. No idea how far away from the survivor that happened.

**Chemistry**

hint: nuclear reaction.

**Math Percents**

P is 150% more than S.

**math**

If h is the height of the building above S, then we have h cot30° = (h-10)cot60°

**Ratios**

If the lightest is x, then the heaviest is 3x. So, 3x = x+8 x = 4 So, the parts are 4,8,12 oz

**math**

x^2+6 is the result, if you started with x.

**Math**

it's still a direct relationship. It just happens that the constant of proportionality is negative. The "amount you lose" increases with the running time.

**math**

I'll get you started... (2n^2-7n+2)*(3n+1) = (2n^2-7n+2)*3n + (2n^2-7n+2)*1 Now just expand each factor term by term, simplifying at the end.

**Math**

1:25 = 20:500

**Science**

avg speed = total_distance/total_time so, just plug in your numbers

**math**

don' see no steenkeng tables, but something like -1 -4 0 -3 1 -2 2 -1 3 0 ...

**math**

c(1+r)(1-0.15) = c what r should be depends on how much profit he expects to make. a 17.6% markup will just break even. a 20% markup will provide a 2% profit.

**Science**

since s = vt = 1/2 at^2, you need 6t = 1/2 * 4 t^2 3t = t^2 t = 3

**science**

?(100^2+70^2)

**math**

Your typing skills can use some improvement as well. I'd say your past laziness is now catching up to you. Too bad. Seek some in-person help. Trying to do it piecemeal here will not cut it.

**Statistic**

so, assume 100 candies, with 15 yellow. Your probability will be approximately 15/100 * 85/99 * 84/98 = 0.11 = 11%

**Math**

c'mon, guy, just write the words as algebra. If the pool has width w, then its length is w+6. Now work with the total area: (w+8)(w+6+8) = w(w+6) + 576 Now solve for w and then w+6.

**Math**

If the ladder has length z, then (.3z)^2+20^2 = z^2 z ? 21 ft

**Math**

just plug in your numbers and solve for h 900 = ?(h^2+8000h) h^2+8000h-900^2 = 0 h = 100

**Math**

If the base is b, then (1/2)bh = 30 (1/2)b(2b-2) = 30 ...

**Geometry**

Draw a side view of the figure. Using similar triangles, it is clear that (9-h)/r = 9/6 h = 9 - 3r/2 Now we can compare volumes, and we find 1/3 pi * 6^2 * 9 = 9 pi r^2 h 108 = 9r^2(9 - 3r/2) r^3 - 6r^2 + 8 = 0 r = 1.3054

**Science**

google the topic, and you will get lots of information.

**Science**

correct

**Geometry**

two ends with total area 2pi r^2 curved side with area 2pi r h area = 2pi*r(r+h) = 748pi

**math**

#3 ok #4 - better check again how many marbles out of 30 are green or purple.

**PLEASE HELP BEEN STUCK ALL DAY CALCULUS**

recall the formula for the area of a trapezoid: A = (B+b)h/2 Its area is the average of the areas of the rectangles formed using the lengths of its bases: the left and right function values!

**scienice**

amplitude and wavelength

**Pre cal**

see your previous post. The horizontal speed is constant.

**Geometry**

the ratio of the volumes is the similarity ratio cubed. so, you want ?(135:625) = ?(5*27:5*125) = 3:5

**Pre cal**

then use that t and multiply by the constant horizontal speed of 110 cos45°

**Pre cal**

just solve for t in h(t) = 2 + (110 sin45°)t - 16t^2 = 0

**math**

a+b+c = 770 a = 2/9 (b+c) ==> b+c = 9a/2 a + 9a/2 = 770 ...

**Physics special relativity**

1ly = 9.454254*10^15 m 1y = 3.1536*10^7 s c = 2.99792*10^8 m/s 23000ly/30y = (2.3*10^4 * 9.454254*10^15)/(30*3.1536*10^7) = 2.298409*10^11 m/s see what the Lorentz factor is for 0.99999915c and I'm sure it will work out.

**maths**

(K+L)/(K-L) divide top and bottom by L: (K/L+1)/(K/L-1) = (7+1)/(7-1) = 4/3

**maths**

convert all to decimals, or use a common denominator of 60. Then comparisons are easy.

**math**

4 vowels, 5 consonants D,C from first half of alphabet How can D or C occupy only the first position? One of them has to be somewhere else in the permutation.

**Precalculus**

z^4+z^2+1 = 0 (z^2-z+1)(z^2+z+1) = 0 one root is z = (1+?3 i)/2 = cis(pi/3) so, z^3 = -1 That means z^6 = 1

**math**

oops. Forgot to edit my id...

**Algebra**

amplitude: (14-4)/2 = 5 center line: (14+4)/2 = 9 so, we can start with y = 9cos(kx) the period is 5+5 = 10 hours, so 2?/k = 10, making k=?/5 y = 9cos(?/5 x) The high tide was at 7:00, rather than midnight, so y = 9cos(?/5 (x-7)) or y = 9cos(?/5 x - 7?/5) see http://www....

**Geometry**

Interesting. I did it like this: 2x+2y = 50, so x+y=25 x+y+h = 40 25+h = 40 h = 15

**Geometry**

works for me. I hope you calculated BD and didn't just guess around till you got a number that worked.

**math**

.09x + .05(20000-x) = 1680

**Geometry**

the distance is ?(12^2+(15-10)^2) = 13 Maybe you should have shown your work.

**geometry**

drop an altitude from M to P on KN. Then PM = ?(15^2-9^2) = 12 the area is thus (9+18)/2 * 12

**Science**

what do you think?

**math**

4.250 anything less, say, 4.249 will round down to 2.2

**math**

4.30 I think

**Math**

each side of the triangle is the sum of two radii.

**trig**

h = 2+10sin58°

**math**

x y -2 9 -1 4 0 -1 1 -6 2 -11 Note that as x goes up by 1, y goes down by 5. So, start with y = -5x Now, y(0) = -1, so the rule is y = -5x-1

**Algebra 2**

take a look at the graphs, and it should be clear. Or, study your text and apply the rules. http://www.wolframalpha.com/input/?i=plot+y%3D1%2Fx,+y%3D1%2F(2x-4)

**Algebra**

(2?5+3?7)^2 (2?5)^2 + 2(2?5)(3?7) + (3?7)^2 4*5 + 2*2*3*?35 + 9*7 ...

**chemistry**

the theoretical yield is 2 moles of CO2 for each mole of C2H6 So, how many moles of C2H6 did you use? how many moles of CO2 in 5.76g? compare your yield with the possible yield.

**Algebra/Trig**

the height the ladder will reach is 12sin75°

**Trig**

h = 2+10sin58°

**Math**

the horizontal speed is constant, at 90cos60° ft/s, so just use that speed for 3 seconds to find the distance.

**math**

just like the previous ball team question. You're not going to put in any effort?

**math**

this is just like the last one. Just write an equation for each statement. To start with, r+w+b = 28 ...

**math**

If they lost x, then x + 3x+14 = 130

**Maths**

the volumes are A:?r^2(8h) = 8?r^2h B:?(4r)^2h = 16?r^2h