math, PLEASE HELP!
posted by gavin
Point E(0, -2) is a vertex of square DEFG. After a 90* clockwise rotation of the square about the origin, which of the following is the location of E?
Point D(-3,5) is a vertex of triangle DEF. After rotation of the triangle about the origin D us located at (3,5). Which of the following was the rotation of the triangle?
A. 90* (degrees) clockwise
B. 90* Counterclockwise
Please help! I don't know anything about this! I'm not asking for the answers, but I need someone to explain this for me!
You know, you can just take a piece of graph paper, and stretch a string from (0,0) to (-2,0) and then rotate the end. You can easily see that (0,-2) -> (-2,0)
For this one, (-3,5) -> (3,5)
So, using your string, you can see that the point was rotated 180°.
I still don't get it, can you give me an example?
What can I say? I worked your two problems, even gave you the answers.
i think you'd better google rotations and read the many examples that will pop up.
I repeat. Get out your string and holding one end at (0,0), place the other end at various places and ROTATE IT! Just DO IT!
Don't do the string thing, it's not practical. You wanna know how to solve mathematicaly. So I'm gonna assume you know clockwise and counterclockwise, I would hope. Ask if you don't. Say you have point (1,0), and you rotate it 90° clockwise around the origin [which is point (0,0)]. It would end up at (0,-1). Another such rotation,it would end up at (-1,0), another one at (0,1), and a 4th one would bring it back to (1,0). Plot those points and see what they look like. Maybe draw lines to them from the origin and see the angles that are formed. Its a really simple thing when there are no zeros in the point's coordinate. So for any (a,b), in which they are both positive (meaning the point is in the first quadrant), you can just change the signs into whatever signs the next quadrant has when the rotations are 90° angles, and invert the numbers. For example, (1,2) rotated 90° counterclockwise (going from 1st to 2nd quadrant) will turn into (-2,1). In the other direction, it would have turned into (-2,-1). I hope that helps a bit more, I feel like my explanation was insufficient.
1 A C D
1 A C D
I got a 100%
He is correct.^
Dd is correct I got 100% trust me will pass it!
1. A C D
2.b -2, 0
3. C180 degrees
4. B 60 degrees
5. C 120 degrees
100% pass just took it trust me will pass I promise I am telling you the truth!
no sorry Katie pickle but I got 80% so number 2 is not B it's A
thanks man,there 100% right