View Full Version : Geometry Help--Finding Each Measure!!!

ToOtSiE_PoP

09-10-2005, 05:46 PM

Help!!!!!!! I need to know how to find each measure....There is a diagram of an obtuse angle, split into one acute angle..(this angle and the angle adjacent are congruent) and a right angle split into 2......in Angle AOB it says (12x-4) and in Angle BOC is says (13x-9)...The other angle, Angle COD...doesnt give me an equation....Then it says find the m<AOB...What do I do!!????!!

stapel

09-10-2005, 05:52 PM

I'm sorry, but I don't understand what you're describing.

You have an obtuse angle. What is its name? You say it is split into "one acute angle", but if an angle is "split", there must be at least two angles resulting from the split. How is it split? By a ray from its vertex? Is it bisected, or is it divided into unequal halves?

You have a right angle. What is its name? You say that it is split into two. Is it bisected, or are the two resulting angle unequal? What are the names of the resulting angles?

How do AOB and BOC relate to any of the forgoing angles? How does COD relate?

Thank you.

Eliz.

ToOtSiE_PoP

09-10-2005, 06:05 PM

Sorry..I was flustered..LOL...Okay...I have an obtuse angle AOD...and it is split into an acute angle from the vertex O (AOB)...so that forms a right angle adjacent to it(BOD)....that right angle is then split inhalf from the vertex O...to form angle BOC and COD....Angles AOB AND BOC are congruent...inside angle AOB it says (12x-4) degrees and inside angle BOC it says (13x-9)degrees...inside angle COD it says nothin....So how do I find the measure of angle AOB, BOC, COD, BOD, AOD, AND AOC????

Thank You In Advance!!

stapel

09-10-2005, 06:13 PM

So you have an obtuse angle, AOD. From O, a ray is extended through B, forming an acute angle AOB and a right angle BOD. Another ray is extended from O through C, forming angles BOC and COD.

You say that this ray splits angle BOD "in half", which means the ray is a bisector, and angles BOC and COD are congruent. Since angle BOD is a right angle, then m(BOC) = m(COD) = 45°. From this, you can solve for the value of x, and then for the measures of the angles.

Eliz.

ToOtSiE_PoP

09-10-2005, 06:17 PM

No...Angle AOB and BOC...are congruent.....So how do you find the answer?? Thanks

stapel

09-10-2005, 06:20 PM

Yes, AOB and BOC are congruent. And since you say that OC divides BOD "in half", BOC and COD are also congruent.

Eliz.

ToOtSiE_PoP

09-10-2005, 06:46 PM

Oh Okay...Duh..So can you please explain how you got this answer?

stapel

09-10-2005, 06:56 PM

I didn't give the answer; I told you how to find it.

Eliz.

ToOtSiE_PoP

09-10-2005, 07:09 PM

Ok...so would the answer for m(BOC) be 45.6..but that makes no sense does it! Im so confused....I dont understand how to solve for x....

This is how I got 45.6....

13x-9=45

+9 +9

13x=54

x=4.2 (rounded)..and I plugged it into the eq...

stapel

09-10-2005, 07:13 PM

You said that BOC was half of a right angle. Where is "45.6°" coming from?

Eliz.

ToOtSiE_PoP

09-10-2005, 07:18 PM

Correct, but inside angle BOC I am given an equation (13x-9) degrees....and b/c BOC is congruent to COD, I wrote 13x-9=45...to solve for x..but I got 4.2 (rounded to nearest tenth)and plugged it into the equation 13(4.2)-9...

stapel

09-10-2005, 07:34 PM

When you round, you're not going to get an exact value. That's the point (and downside) of rounding. And plugging the rounded value back into the angle-measure expression doesn't change the actual angle measure. If the angle measure is 45°, then it's 45°, not 45.6°.

Eliz.

ToOtSiE_PoP

09-10-2005, 07:52 PM

I am still confused about how I am to find each measure....How do I find the answer for m(BOC) using the equation.....I understand m(cod) is 45 degr....but I need to show steps showing that m(BOC) =45 degr...(since its = to COD) but I dont get how I am to get 45 degr..using the equation...

stapel

09-10-2005, 08:14 PM

You said that BOD was split in half to form BOC and COD. Don't they have the same angle measure then, since they're each one half of the original angle?

And you said that BOD was a right angle. What is the measure of a right angle? What is half of that?

Eliz.

ToOtSiE_PoP

09-10-2005, 08:22 PM

45 degrees..so why is this equation inside BOC..(13x-9)? Inside AOB..there is also an eqaution inside that (12x-4) degrees...and it is congruent to BOC which is 45 degrees...but arent I supposed to use these equations to find each measure???? How do I solve for x to get each measure?? Am I supposed to use each equation like 12x-4=180...I am confused...

stapel

09-10-2005, 08:39 PM

The angle measure is being given as "13x - 9". Set this expression equal to the known value, and solve for x. Don't round the answer.

The problem comes, of course, when you don't get "45" as the answer for the measure of the angle that is supposed to be congruent, which leads me to wonder if you have yet presented the exercise accurately. Does OC really split BOD "in half"? Or just "into two angles"? Is there any other information in the drawing?

Eliz.

ToOtSiE_PoP

09-10-2005, 10:11 PM

"Angles AOB AND BOC are congruent"...Only these angles are congruent...The drawing doesnt state that angles BOC and COD are congruent....So the right angle is bisected into 2 differnet angles...

stapel

09-10-2005, 10:23 PM

the right angle is bisected into 2 differnet angles...

"Bisected" means "split exactly in half". You can't cut something into to equal but not equal parts. Is the right angle bisected, or is it cut into two different angles?

If the angle is bisected, then the algebraic expressions don't work out. If it is not, then solve for x and see where that takes you.

Eliz.

ToOtSiE_PoP

09-10-2005, 10:33 PM

sorry typo..those angles are split into 2 seprate angles...only angles AOB and BOC are congruent....

ToOtSiE_PoP

09-10-2005, 10:51 PM

I don't understand this drawing at all...It needs to specify the measurement of the whole angle...AOD...Oh wait I am supposed to find the measurement of that angle too...I was trying to draw something like the drawing Iam referring to....no such luck...If you have time..can you draw what you think looks like the drawing I am referring to? Its really frustrating!!

(12x-4) Degrees (13x-9)Degrees

^ ^

l ^ l B ^ /

l l /C AOB and BOC are =

l l / BOD Makes a Right Angle

l l / **Looks something like this... A l l / COD is more to the right thou...

l l /

l l/______________

O D

Denis

09-10-2005, 11:06 PM

Angles AOB AND BOC are congruent...inside angle AOB it says (12x-4) degrees and inside angle BOC it says (13x-9)degrees...

Darn it Tootsie, if they're congruent, they're EQUAL; then:

13x - 9 = 12x - 4

x = 5

12(5) - 4 = 60 - 4 = 56

13(5) - 9 = 65 - 9 = 56

That's IT ; OVER AND OUT : those 2 angles both equal 56 degrees...

if that changes anything in your problem, then go see your $#%@#$@!@

teacher with it and tell him/her to smarten up :)

ToOtSiE_PoP

09-10-2005, 11:25 PM

Oh my goodness!!!!! Thank You sooo much...this is such a DUH answer!! My teacher just goes over the same exact lessons in the book and then he assigns us homework that we dont know how to do...then we dont even check the homework to see if we FIGURED the stuff out RIGHT!!!

Thanks again!!!!!

BTW If you want to draw something here, click the Code button twice then type between the boxes. That keeps ti from colapsing.

C

/|

/ |

/ |

/ |

/ |

/ |

A__________B

Denis

09-11-2005, 08:37 AM

Your hypotenuse ain't straight, Gene...

stapel

09-11-2005, 10:13 AM

His triangle is pretty good; it gets the idea across. It's just that not all of us are as good as Soroban when it comes to graphing. :wink:

Eliz.

Denis

09-11-2005, 03:10 PM

His triangle is pretty good; it gets the idea across. It's just that not all of us are as good as Soroban when it comes to graphing. :wink: Eliz.

Well, anybody is better than me!

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