1.5 Bisecting Segments and Angles
Sep 19th, 2011 by corricelli
Hello,
Please use this section to ask questions, provide links for teammates that might help them, and/or to work together.
HW Due Wed, 9/21: p. 38: 19, 21, 25, 29, 31, 33, 37, 45-49 odd, 53
Happy Blogging (and Bisecting!),
Mrs. Corricelli
Hi, What did you mean when you said notate the angles on page 37?
An,
On number 37, you needed to find the two angle measures not given. So, notating your response is good practice so that you know which angle measure should be paired with which angle. For example, because m<PQS = 22 degrees is good notation. However, just 22 degrees is not clear. <PQS = 22 degrees is not correct. The MEASURE is 22 degrees, not the angle itself. The angle is an angle, not a measure.
The complete (and correct) answer to 39, which is a really similar question is:
m<SQR = 80 degrees
m<PQR = 160 degrees
Hope this helps,
Mrs. Corricelli
what is the formula to find the missing endpoint??
Shane,
See the bottom of page 35. Amalia is 100% right; you are using the midpoint formula and backing out of it. Try to avoid, if you can, memorizing formulas. Try to remember to concepts/derivations – this skill will serve you well in geometry.
Follow the example as is…
Mrs. Corricelli
Shane,
See my reply. I did 27, which is the same approach, to provide further support.
Hope this helps,
Mrs. Corricelli
I had trouble on numbers 25 and 29 anyone know how to solve them?
Annie,
These examples are just like example 2 on page 35 (which we did together in class). The trick is there is no obvious “formula”; you are backing out of the midpoint formula. Rewrite example 2 slowly and try to understand each step. THEN try these examples.
Hope this helps,
Mrs. Corricelli
Annie,
See my reply to Amalia. I did 27, which is the same approach, to provide further support.
Hope this helps,
Mrs. Corricelli
Thanks for letting me know about the extra help in room 168!
Matt,
You are welcome! Did it help today?
Thanks,
Mrs. Corricelli
The formula to finding the missing endpoint is:
(X1,Y1) and (X2, Y2) is:
(average of x’s,average of y’s)
( (X1+X2)/2,(Y1+X2)/2 )
Sorry if it looks confusing I don’t really know how to type that..
And I also had difficulty on 25 and 29 as well.
Amalia,
Same advice I gave to Annie.
These examples are just like example 2 on page 35 (which we did together in class). The trick is there is no obvious “formula”; you are backing out of the midpoint formula. Rewrite example 2 slowly and try to understand each step. THEN try these examples.
If you have a lightbulb moment, share!
Take care,
Mrs. Corricelli
Shane, Annie, and Amalia: (and anyone else)
Lets look at 27:
midpoint = ((x1+x2)/2, (y1+y2)/2)
(2, -1)=((3+x)/2, (-12+y)/2) since they give us midpoint (2, -1) and one endpoint (x1,y1)=(3, -12)
So, 2 = (3+x)/2 and -1 = (-12 + y)/2.
Multiplying both equations by 2 to get rid of 2 in the denominator,
4=3+x and -2 = -12 +y
Adding -3 and 10 to each side, respectively, x = 1 and y = 10.
So the other endpoint is (1, 10).
25 and 29 use the same approach.
Again, take this slowly and work through.
Hope this helps,
Mrs. Corricelli
Thanks Mrs.Corricelli!
http://www.google.com/imgres?q=ballet+45+degrees&um=1&hl=en&sa=N&biw=1152&bih=625&tbm=isch&tbnid=EczL9MW0qzm1tM:&imgrefurl=http://danceinjuryrecovery.blogspot.com/2010_05_01_archive.html&docid=WYXAi-GgA3d62M&w=896&h=600&ei=NICITtvaJafc0QGCsKwL&zoom=1&iact=hc&vpx=404&vpy=305&dur=506&hovh=118&hovw=153&tx=98&ty=74&page=1&tbnh=118&tbnw=153&start=0&ndsp=19&ved=1t:429,r:8,s:0
This photo is an example of a 90 degree angle, also known as a right angle in geometry. A right angle is half of a 180 degree angle also known as a straight line. i have taken ballet for eight years so i am very familiar in these angles.
http://www.google.com/imgres?q=ballet+a+split&um=1&hl=en&biw=1152&bih=625&tbm=isch&tbnid=Xq7NCdquegIyCM:&imgrefurl=http://www.academyofballetandjazz.ca/testimonials.html&docid=yg17_TMzxZdGVM&w=300&h=297&ei=qYGITpTcJcnSgQeU3e35Cg&zoom=1&iact=hc&vpx=864&vpy=288&dur=17138&hovh=223&hovw=226&tx=154&ty=215&page=1&tbnh=135&tbnw=149&start=0&ndsp=16&ved=1t:429,r:15,s:0
This is an example of a straight line (180 degrees). Usually anytime someone is doing a full split they are automatically going into a 180 degree angle. this is how geometry is orchestrated into ballet .