Easy pts, Dumb Questions: Part II

[101dalmatians]

Degree mode is stupid. It gives me wrong answers in solvers.

Mr. Woofer can roof a house in 6 days by himself. If his son helps him, they can finish in 4 days. How long would it take for the son if Mr. Woofer didnt help?
An easy formula please.

Ugh... Again! Kinds of numbers. I have to face it!

The graph of [unparseable or potentially dangerous latex formula] is symmetric with respect to what?
I know how to graph it but i feel i would spend less time if i didnt. so any other way?

[007math]

[101dalmatians]

[101dalmatians]

Now vectors:

[unparseable or potentially dangerous latex formula]

Then is speed = [unparseable or potentially dangerous latex formula] b/c of the absolute value?

[007math]

[101dalmatians]

[007math]

Do you still need an explanation for the work problem?

[101dalmatians]

[007math]

[101dalmatians]

Thanks :)

[101dalmatians]

So... I'm making this rate problem up and I just wanted to know whether I did it right.

I mow a lawn in 3 hours. My friend mows a lawn in 5 hours. How long would it take if both of us mowed a lawn together?

Alright So this is what I got: [unparseable or potentially dangerous latex formula]. Is it right? If not, what did I do wrong?
My method: I just added up 1/5 and 1/3 and took its reciprocal.

[darksaber21]

Yes, that is correct.

[101dalmatians]

[101dalmatians]

Mr. White, a trimmer and fitter man, continues his morning walks with his collie, Lady. Based on the info below, what is the length of his walking stride?

[unparseable or potentially dangerous latex formula]

Sorry the latex got messed up a little but its kinda clear.

[darksaber21]

You need to average out the rates to determine his speed:

[unparseable or potentially dangerous latex formula]

[unparseable or potentially dangerous latex formula]

[101dalmatians]

Thanks :D

[101dalmatians]

Find an identity for [unparseable or potentially dangerous latex formula] for all defined values of x.

[darksaber21]

[101dalmatians]

Cool!
But on my 89, I dont get the simplification that I usually get.
do I substitute [values] at these points in time?

[nsguy1350]

[darksaber21]

You don't really need to use complex numbers to solve it. You basically just use the sum/difference formula and the identities like [unparseable or potentially dangerous latex formula], [unparseable or potentially dangerous latex formula] and [unparseable or potentially dangerous latex formula] multiple times.
But the method of using complex numbers is pretty interesting nonetheless.


And anyway, the 89 doesn't usually simplify things that easily. It works from time to time, but you are better off simplifying equations by hand.

[101dalmatians]

Thanks :P

[nsguy1350]

That is true, but I like the complex number method. I'll put it here, for others to see, since I believe it's interesting.

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

By De Moivre,

[unparseable or potentially dangerous latex formula].

Equating the real and imaginary parts,

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

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


Therefore, [unparseable or potentially dangerous latex formula] and [unparseable or potentially dangerous latex formula].

[101dalmatians]

How do you no this stuff dude? Not b/c ur nsguy right? Pls dont say so.
Where do u learn this - like from wikipedia or what?

[nsguy1350]