TRUE or FALSE? When Point E (-2, -5) is rotated 270° counterclockwise about the origin, it becomes (-5, 2).

Question

vera_ewing · Answer

@wio

vera_ewing · Answer

@amistre64 please help me!

amistre64 · Answer

any way to check it that you know of?

vera_ewing · Answer

well i guess i could do the actual problem? lol

amistre64 · Answer

lol, that would be one method yes.  i know of several more

vera_ewing · Answer

oh really? like what?

amistre64 · Answer

well, since 270 = -90,  then the dotproduct of the 2 vectors would equal 0, and have the same length

amistre64 · Answer

another method is a rotation matrix

-2cos(270)  +5sin(270) = 5
-2sin(270)   -5cos(270) = -2

vera_ewing · Answer

ok so its false?

amistre64 · Answer

did you work your method?  or is that just a guess?

vera_ewing · Answer

well i worked the method with the rotation matrix

amistre64 · Answer

-2,-5
-5,  2
------
10-10 = 0  so they are 90 from each other.

|dw:1404334565087:dw|

im getting false as well this way