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Mathematics 23 Online
OpenStudy (allen27):

@mathstudent55

OpenStudy (allen27):

OpenStudy (allen27):

G: Triangles DEF and DEG; m Given 2. Definition of Congruent Angles 3. Reflexive Property of Congruence 4. Triangle DEF is similar to Triangle DEG --> Angle-Angle Triangle Similarity Postulate is that correct?

OpenStudy (mathstudent55):

No. You need to start with the given info. The given info here is the angle measures that are shown in the figure. Then you need to show that two angles of one triangle are congruent to two angles of the other triangle you are proving similar. Then you use AA similarity as a reason to state that the triangles are congruent.

OpenStudy (mathstudent55):

A two-column proof starts with a two-column set up with statements and reasons.

OpenStudy (allen27):

i know that part

OpenStudy (mathstudent55):

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OpenStudy (mathstudent55):

Now I'll just write using text bec it's easier than using the figure, but keep the correct format by using the setup above.

OpenStudy (mathstudent55):

1. m<DEG = 60 deg 1. Given 2. m<EFG = 60 deg 2. Given 3. m<DEG = m<EFG 3. Substitution property of equality 4. \(\angle DEG \cong \angle EFG\) 4. Definition of congruent angles.

OpenStudy (mathstudent55):

That already proved one pair of angles is congruent. For AA Similarity, we need a second pair of angles. Do you see another pair of angles, one in one triangle and one in the other triangle that are congruent?

OpenStudy (mathstudent55):

Sometimes, separating the triangles makes it easier to see. |dw:1467921836696:dw|

OpenStudy (allen27):

so the proof u wrote on the tope is the anwser?\

OpenStudy (mathstudent55):

Angle F of triangle DEF is congruent to angle E of triangle DGE. Is there a second pair of congruent angles we can see from the figure?

OpenStudy (mathstudent55):

Are you reading what I am writing? I have proved one pair of angle congruent. We need a second pair of angles congruent. I am waiting for you to read what I wrote and participate. I am waiting for your answer to go on.

OpenStudy (allen27):

im reading

OpenStudy (mathstudent55):

Great.

OpenStudy (allen27):

is their 3 congruent angles in all?

OpenStudy (mathstudent55):

Remember what we discussed above. To use AA similarity to prove two triangles similar, you need two pairs of congruent triangles. The figure showed that two angles measure 60 degrees. One 60-deg angle is in one triangle, and the other 60-deg angle is in the other triangle. These two angles, then, can be used as one pair of congruent corresponding angles. Now we need a second pair of angles, one angle from each triangle, that from looking at the figure, we know for sure are congruent.

OpenStudy (allen27):

so d is congruent to d and from triangle efd e is congruent to g on triangle egd

OpenStudy (mathstudent55):

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OpenStudy (mathstudent55):

That is exactly it. You got it. This is the key to this problem.

OpenStudy (allen27):

can you just tell me the answer it'd be much appreciated

OpenStudy (mathstudent55):

In geometry, we are not allowed to conclude angles are congruent by the way they look in a figure. In this case, angle D is an angle of both triangles, so angle D is congruent to angle D, and that is the other pair of corresponding angles that are congruent.

OpenStudy (mathstudent55):

Now we continue with the proof.

OpenStudy (allen27):

k

OpenStudy (allen27):

idk how to do this proof i only know the basics

OpenStudy (mathstudent55):

5. \(m\angle D = m\angle D\) 5. Reflexive property of equality 6. \(\angle D \cong \angle D\) 6. Definition of congruent angles 7. \(\triangle DEF \sim \triangle DGE\) 7. AA similarity

OpenStudy (mathstudent55):

That is the rest of the proof.

OpenStudy (allen27):

thank you very much

OpenStudy (mathstudent55):

Once the two pairs of angles are shown to be congruent, you can use AA similarity to justify that the triangles are similar.

OpenStudy (mathstudent55):

You're welcome.

OpenStudy (allen27):

iv been sitting here for an hour trying to get an anwser to one of my question outof the 135 questions i need to do

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