All Junior Cert Technical Graphics posts
• #### Rotations!!! Aoife24

In transformation geometryI know how to get the point and swing the arcs I just have no idea how to get the points on the arcs! Someone help !

1. #### DylanG

Join the point you're rotating to the point you swung your arcs from, then use your protractor to bring the angle off at 120.. Hope this help ! If you're still stuck then let me know

2. #### frans

how to get the point of rotatation ? (eg rotate clockwise through 90 degrees ?

3. #### DylanG

It's usually the last thing you do in transformation geometry so join p3 to p4 then draw an angle at 45 from p3 and p4 until they meet them that's your rotation point

4. #### DylanG

Is its rotate at 120 then use a 30 angle instead 45 angle

5. #### Aoife24

If it's 90 degrees you use a 45 angle abs if it's 120 or 60 you use a 30 degree angle

6. #### DylanG

No if its 60 would you not use a 15 angle

7. #### Aoife24

No you use 30 aswell! Cause the formula is subtract the angle they give you from 180 them divide by two!

8. #### Aoife24

I used to think it was 15 aswell I got really confused

9. #### DylanG

You would use a 15 angle

10. #### studybuddy15

Hope it helps.

11. #### DylanG

Anyway I've never seen a rotation at 60

12. #### Aoife24

Actually I don't know that's just what I was told but it really doesn't matter cause the only ones that come up are 120 and 90

13. #### DylanG

What questions do you do ?

14. #### Aoife24

From the exam papers

15. #### Aoife24

I'm still really struggling with finding the points :/ I tried both the ways said here but I don't really understand them

16. #### DylanG

Look up a sample answer in YouTube and try a few yourself ! Even if you don't wanna do the whole transformation geo question just draw the shape out and put another point randomly on the page and try a rotation

17. #### DylanG

I've never used studybuddy15's was

Way*

19. #### Aoife24

Okay thank you!