/sci/ I think my hands look weird. Do they? Is this medically explainable? Or do I just have poor self-image.

Let A and B be non zero real numbers such that a+b>=0

show that (equation in pic)

The acute angle A is such that sinA = 3/5
The obtuse angle B is such that sinB = 5/13
Find without using a calculator cos(A+B)

I'm trying to learn trig on my own and I can't figure out this question. Can anybody help me?

1=9

I'd like to discuss a topic that's been bugging me for a while.

Does the amount of sleep one gets affect his final adult height?

I often find that I'm just shorter than my peers. I know for a fact that I sleep significantly less than them, and many of the "tall guys" sleep way more than average. This is from a tiny sample size of ~8 people though. My diet is pretty typical, so I doubt it has any relevance.

thanks in advance, /sci/

>American textbooks
>as informative as the underside of a snapple cap

sci, i need your help.
assignments already one day overdue.
can you help me please?

pic related

A horse has 64 chromosomes.
A donkey has 62 chromosomes.
A mule is a mixture of both and has 63 chromosomes.
mfw mules are donkeys with down syndrome.

Math help required. I just want to know how to attack related rates of change questions: at the moment I'm completely confused with them. I've got a sample question that I'm trying to do, I'll post that if it helps to have an example to explain, but really I need help with related rates of change in general.
Here's the question I tried:

At time 't' seconds, the length of the side of a cube is 'x' cm, the surface area is 'S' cm^2, and the volume of the cube is 'V' cm^3.

The surface area of the cube is increasing at a constant rate of 8cm^2/s. Show that:

(a) dx/dt = k/x, where k is a constant to be found

(b) dV/dt = 2V^(1/3)


I understand that you need to use S = 6x^2, to obtain dS/dx or V = x^3 to obtain dV/dx etc. However I don't know what to do with them and anything I do try is just messing about since I don't know why I'm doing it. Help greatly appreciated.

Also I have watched the related rates of change videos on khanacademy and I'm still at a loss.

why haven't we evolved to not need sleep?