B Prove Bisecting Angle Theorem - 5 Min Exercise

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The exercise presented involves proving the bisecting angle theorem with the equation m(∠EAD)=[m(∠ABC)-m(∠ACB)]/2. Participants noted that the proof is generally not valid without additional conditions on point D, as varying D along line BC results in multiple values for angle EAD. The original poster acknowledged the oversight of not specifying that AD bisects the angle into two equal angles. The discussion highlights the importance of clear conditions in geometric proofs. The thread was ultimately closed for moderation.
Qemikal
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Hi, guys, i made an exercise, can you prove this?
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m(∠EAD)=[m(∠ABC)-m(∠ACB)]/2
If you have 5 free minutes, try it, i hope you'll like it!
It's my first own exercise, so I would like some feedback, too.
AD= bisecting(splits angle in 2 equal sides)
 
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You can't prove this, it is, generally, not true. By choosing D at different places along BC, angle EAD can take on many different values while the right side, not depending on D, is fixed. Was there some other condition on D you did not give?
 
HallsofIvy said:
You can't prove this, it is, generally, not true. By choosing D at different places along BC, angle EAD can take on many different values while the right side, not depending on D, is fixed. Was there some other condition on D you did not give?
My bad, I forgot to add that AD splits the angle in 2 equal sides(angles).
 
Thread closed for moderation.
 
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