Hello there, I'm not from a country where many mathematics

you have to go de vuelta a tu puto pais
also, just apply: [math] e^{i \theta} = cos( \theta )+i \space sin( \theta )[/math]

>>8515677

Can you explain how this works in detail? Are you saying that this identity can be applied to any scenario? Most of my research suggests a "Left Side, Right Side" method.

>>8515658
let the unit vector in the x axis (1, 0) be
⌈1⌉
⌊0⌋
and the unit (basis) vector in the y direction be
⌈0⌉
⌊1⌋
Then the matrix A(ϕ) that rotates (counter clockwise) a vector by ϕ will take the unit vector in x direction to
⌈cos(ϕ)⌉
⌊sin (ϕ)⌋
and takes the y vector to
⌈-sin(ϕ)⌉
⌊cos(ϕ)⌋
Thus A(ϕ) equals
⌈cos(ϕ) -sin(ϕ)⌉
⌊sin (ϕ) cos(ϕ)⌋
Therefore the unit vector at θ to the x axis will be rotated to θ+ϕ after applying A(ϕ)
⌈cos(ϕ+θ)⌉=⌈cos(ϕ) -sin(ϕ)⌉*⌈cos(θ)⌉
⌊sin (ϕ+θ)⌋=⌊sin (ϕ) cos(ϕ)⌋*⌊sin (θ)⌋

Multiply out to get the relationships of the angle sum to the product

>>8515704

I'm sorry, sir. Trigonometric identities don't involve angles. I found this resource: http://www.purplemath.com/modules/proving.htm

The trick is to memorize the shit out of them.

>>8515799

Why are the Western kids evaluated on their ability to memorize and not on their abilities?

Thank you.

>>8515677
Mate do you really think he is going to understand what that even means? I dont even get it and I'm in calculus