Lol you're retarded

no seriously i have a calc 2 exam in two hours, and this is calc 1 shit, pls help

>tfw I never had to take another math class in college since freshman year 
feelsgood.jpg

you can get -0.5*cos^2 and 0.5*sin^2

don't sweat it, you're right.

you can get -0.5*cos^2 and 0.5*sin^2

don't sweat it, you're right.

wolfram alpha says otherwise. also, if you evaluate it from 0 to 2pi (this is just part of a longer problem), you get 0, but it should be 3... it is 3 if you go the cosine route, but yeah.

Because sin^2x/2 is just sin^x

what

Quote from: Ingloriouswho98 on November 17, 2015, 02:38:30 PM

Because sin^2x/2 is just sin^x

what

Nevermind

I was thinking of something else

I remember having to do this shit

Math sucks.

Holy shit what the fuck are you guys doing?

Rc asked for help, he gets help, but then these motherfuckers show up and start talking about how they used to do the same thing, and how the world has changed for them.

What is with you people?

What I'm trying to say in my autistic ramblings is that your platitudes aren't doing anything for the thread, so you must be doing it for yourselves, which is fine in some threads, but this thread isn't a thread for discussion about personal experiences or whatever. This is a thread specifically about a certain math problem.

also, 'mirin peoples' math skills.

Quote from: rc on November 17, 2015, 02:42:41 PM

Quote from: RadioactiveTurkey on November 17, 2015, 02:42:12 PM

Quote from: rc on November 17, 2015, 02:11:50 PM

how the fuck is sin^2(x)/2 NOT the integral of sinxcosx?

There are two correct answers.

"Not always" doesn't mean "isn't".

also, if you evaluate it from 0 to 2pi (this is just part of a longer problem), you get 0, but it should be 3... it is 3 if you go the cosine route, but yeah.

Well your u/du substitution is correct so just use that. Wolfram sucks ass at trig calc. It's different based on which factor you use for u.

.5sin^2(x) + C = -.5cos^2(x) + c, but their constants are not equal.

Why do I get two different answers when I evaluate it though? I just wanna understand what went wrong.

Because my understanding is that the constant doesn't matter when you're solving a definite integral.

Quote from: The Meta Madman Destyyy👌 on November 17, 2015, 03:45:16 PM

Holy shit what the fuck are you guys doing?

Rc asked for help, he gets help, but then these motherfuckers show up and start talking about how they used to do the same thing, and how the world has changed for them.

What is with you people?

What I'm trying to say in my autistic ramblings is that your platitudes aren't doing anything for the thread, so you must be doing it for yourselves, which is fine in some threads, but this thread isn't a thread for discussion about personal experiences or whatever. This is a thread specifically about a certain math problem.

also, 'mirin peoples' math skills.

Read the thread, people helped him

Good God man read before you type a wall

Read the reply, I wrote that people helped him.

Quote from: Val 'Ketamai on November 17, 2015, 03:57:26 PM

Quote from: The Meta Madman Destyyy👌 on November 17, 2015, 03:45:16 PM

Holy shit what the fuck are you guys doing?

Rc asked for help, he gets help, but then these motherfuckers show up and start talking about how they used to do the same thing, and how the world has changed for them.

What is with you people?

What I'm trying to say in my autistic ramblings is that your platitudes aren't doing anything for the thread, so you must be doing it for yourselves, which is fine in some threads, but this thread isn't a thread for discussion about personal experiences or whatever. This is a thread specifically about a certain math problem.

also, 'mirin peoples' math skills.

Read the thread, people helped him

Good God man read before you type a wall

Read the reply, I wrote that people helped him.

who cares if we mention we used to do calculus?

just you

http://www.wolframalpha.com/input/?i=is+integral+of+sintcost+%3D%3D+-.5cos%5E2t
http://www.wolframalpha.com/input/?i=is+integral+of+sintcost+%3D%3D+.5sin%5E2t

how the fuck is sin^2(x)/2 NOT the integral of sinxcosx?

here's how i got sin^2(x)/2

integral(sinxcosxdx)
u=sinx
du=cosxdx
integral(udu) = (u^2)/2
sin^2(x)/2 + c


THIS IS FUCKING CORRECT WHY IS IT NOT

the integral of sinxcosxdx isn't sin^2(x)/2
it's sin^2(x)/2 + C

sin^2(x) + cos^(x) = 1
sin^2(x) = 1 - cos^2(x)
sin^2(x)/2 = .5 - cos^2(x)/2

sin^2(x)/2 + C is equivalent to  -cos^2(x)/2 + C

Quote from: rc on November 17, 2015, 02:11:50 PM

http://www.wolframalpha.com/input/?i=is+integral+of+sintcost+%3D%3D+-.5cos%5E2t
http://www.wolframalpha.com/input/?i=is+integral+of+sintcost+%3D%3D+.5sin%5E2t

how the fuck is sin^2(x)/2 NOT the integral of sinxcosx?

here's how i got sin^2(x)/2

integral(sinxcosxdx)
u=sinx
du=cosxdx
integral(udu) = (u^2)/2
sin^2(x)/2 + c


THIS IS FUCKING CORRECT WHY IS IT NOT

the integral of sinxcosxdx isn't sin^2(x)/2
it's sin^2(x)/2 + C

sin^2(x) + cos^(x) = 1
sin^2(x) = 1 - cos^2(x)
sin^2(x)/2 = .5 - cos^2(x)/2

sin^2(x)/2 + C is equivalent to  -cos^2(x)/2 + C

but the constant doesn't matter in a definite integral, right?