How are the coordin… - QuestionCove
OpenStudy (nvidiaintely):

How are the coordinates of the new point found if it is rotated 90° counterclockwise? How many degrees is that equivalent to if the rotation is clockwise?

1 year ago
OpenStudy (nvidiaintely):

@Kevin

1 year ago
OpenStudy (kevin):

360-90 = 270

1 year ago
OpenStudy (nvidiaintely):

How are the coordinates of the new point found if it is rotated 180° counterclockwise? How many degrees is that equivalent to if the rotation is clockwise?

1 year ago
OpenStudy (will.h):

am too bored seriously and too lazy i will just watch Kevin solving problems

1 year ago
OpenStudy (nvidiaintely):

lol

1 year ago
OpenStudy (kevin):

okay... for the first question we should find the matrix rotation $M = \frac{ \cos180 \times -\sin180 }{ \sin 180\times \cos 180 }$ $= \left[\begin{matrix}-1 & 0 \\ 0 & -1\end{matrix}\right]$ so, for any (x,y) rotated by 180 degree would be $(x,y) \times \left[\begin{matrix}-1 & 0 \\ 0 & -1\end{matrix}\right]$ = (-x, -y)

1 year ago
OpenStudy (will.h):

I wonder what's he typing. i never seen him typing like that before

1 year ago
OpenStudy (kevin):

I was typing the equation will.... lol

1 year ago
OpenStudy (will.h):

lol i will just watch.. looks pretty nice work keep going mate

1 year ago
OpenStudy (kevin):

wait,, it's 90 degree

1 year ago
OpenStudy (kevin):

OMG I'm writing again o_O

1 year ago
OpenStudy (will.h):

i don't think you needed to use all that tri functions

1 year ago
OpenStudy (kevin):

You have more simple method?

1 year ago
OpenStudy (will.h):

well there's simple form 90 degrees counterclockwise (x,y) --> (-y,x) that's a constant fact you don't need to prove anything

1 year ago
OpenStudy (kevin):

lol.. Honestly, my teacher never teach me like that xD He just give me the matrix rotation formula.. Thx anyway will!

1 year ago
OpenStudy (will.h):

lol sure np your teacher loves to show off lol

1 year ago
OpenStudy (kevin):

xD

1 year ago