Geometry High School- Help

AAA

AAA

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Hi,


Can someone give me a step to step explanation or simply easy steps to solve this problem?
 

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AAA said:
Hi, Can someone give me a step to step explanation or simply easy steps to solve this problem?
Click to expand...

1615128618736.png

The quadrilateral BACD is a trapezoid (Why?)

Apply Parallel line theorem (sum of interior angles = 180o) and solve

Alternatively,

mDCB = mCBA

Now apply theorem of sum of angles in a triangle (CBA) and solve.....
 
Ok. I will solve it and send you my steps. Can you check them for me?
 
AAA said:
Ok. I will solve it and send you my steps. Can you check them for me?
Click to expand...
Post your work here - in Geometry forum and in your thread - you will have lot of help.
 
Thank you. So here: I know that the total angles of any triangle should equal 180 degrees. Is that right? So since I have two angles of BCD; like two triangles. You know what I mean? I then calculated the third angle which is X.

100+30=130

130+ ?= 100 degrees

So 180-130 gives me 50. Is that the answer?
 
AAA said:
Thank you. So here: I know that the total angles of any triangle should equal 180 degrees. Is that right? So since I have two angles of BCD; like two triangles. You know what I mean? I then calculated the third angle which is X.

100+30=130

130+ ?= 100 degrees

So 180-130 gives me 50. Is that the answer?
Click to expand...
Your numerical answer is correct. But I do not follow your reasoning. Have you studied "two column proof"?
 
No what is "two column proof"? I didn't study that.

And If i got the answer correct than my reasoning is correct too. Obviously,
 
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What in my reasoning do you not agree with?
 
130+?=100 degrees. means that 130+ an unknown number or x= 100 degrees. You get it?
 
AAA said:
Can someone give me a step to step explanation or simply easy steps to solve this problem?
Click to expand...
You are given a quadrilateral with opposite sides of equal length. So what sort of figure is is it,
What do you know about consecutive angles is such?
 
I made it myself in order to figure out my answer. They are the angle measures on the triangle. Take a look at the pic I sent you.
Subhotosh Khan said:
No I don't get it!

Where did that equation (130+?=100) - come from?
Click to expand...
 
AAA said:
No what is "two column proof"? I didn't study that.

And If i got the answer correct than my reasoning is correct too. Obviously,
Click to expand...
No absolutely not!

You may write:

(95)/(19) = (95)/(19) = 5 ........ answer is correct but reason is absurd (not even wrong!)
 
It's not absurd. Maybe if I write it THAT way with an x instead of a question mark it would be more clearer. 130+x=100. All math problems uses this reasoning.
 
AAA said:
It's not absurd. Maybe if I write it THAT way with an x instead of a question mark it would be more clearer. 130+x=100. All math problems uses this reasoning.
Click to expand...
Do you realize that in that equation x = - 30 and NOT 50 !!
 
OOPs! I get what you mean now.
 
Last edited:
I meant 180 degrees minus 30= 50. Thats the equation I meant.
 
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