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## #1 2020-08-10 00:33:01

sybil8464
Member
Registered: 2020-08-01
Posts: 8

### Geometry angle of rotation

Thanks for your help. I am struggling with these rotations. I don't see very well and I can, with my audio tools, have the text spoken out loud and but it does not describe the pictures well except to say A and B.

What angle of rotation will take point A and map it onto point B?

My sister tells me it is 12 pt star mapped onto a coordinate plane, with exactly 30 degrees between each point.
Point A is at the very top straight up on the Y axis and Point B is in the bottom left quadrant 30 degrees to the left of the Y axis.

So if I map point A onto point B, I get 210 degrees as my answer. But what if I mapped it the other way bringing A to the left of the plane onto B? It would be 150 degrees. I am unsure which answer is correct and which to use.

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## #2 2020-08-10 19:36:53

Bob
Registered: 2010-06-20
Posts: 8,931

### Re: Geometry angle of rotation

hi sybil8464

Welcome to the forum.

From the way you have described this, either answer is correct.  The question setter needed to say clockwise or anticlockwise.  Normally one would give the lower value ( 150 ) but, unless the wording makes it clear, 210 would also be good.  In some areas of mathematics anticlockwise is the norm, so I'd suggest you say 150.

Hope that is good,

Bob

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

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## #3 2020-08-11 03:38:12

sybil8464
Member
Registered: 2020-08-01
Posts: 8

### Re: Geometry angle of rotation

Thank you for explaining.

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