Segments in circles - 2 column proofs - video issue
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I've been revising some geometry theorems, watching YouTube videos made by @The Organic Chemistry Tutor. I found 2 issues, which I'm not sure about.
in first video
The proof starts at 5:40. In step 4, in the column proof (at 6:54) he says that segment BD is perpendicular to segment AC. I don't understand how come, assuming all we know are the givens in the example, bisector BD doesn't have to be perpendicular, or am I wrong?
in second video
It starts at 2:50. He says "You need to know that if 2 chords od a circle are equidistant from the centre, then they are congruent". and then "Because segment EF is congruent to segment EG, then chord AB is congruent to CD" I thought that EF has to be perpendicular to AB and EG has to be perpendicular to CD to say that the chords AB and CD are congruent, or am I wrong?
I'm a bit confused, as both videos have many likes, so I think I might be wrong. Thanks in advance for correcting me if I'm wrong.
geometry
asked Dec 9 '18 at 22:28
JakJak
274
$endgroup$
|
show 2 more comments
$begingroup$
I've been revising some geometry theorems, watching YouTube videos made by @The Organic Chemistry Tutor. I found 2 issues, which I'm not sure about.
in first video
The proof starts at 5:40. In step 4, in the column proof (at 6:54) he says that segment BD is perpendicular to segment AC. I don't understand how come, assuming all we know are the givens in the example, bisector BD doesn't have to be perpendicular, or am I wrong?
in second video
It starts at 2:50. He says "You need to know that if 2 chords od a circle are equidistant from the centre, then they are congruent". and then "Because segment EF is congruent to segment EG, then chord AB is congruent to CD" I thought that EF has to be perpendicular to AB and EG has to be perpendicular to CD to say that the chords AB and CD are congruent, or am I wrong?
I'm a bit confused, as both videos have many likes, so I think I might be wrong. Thanks in advance for correcting me if I'm wrong.
geometry
asked Dec 9 '18 at 22:28
JakJak
274
$endgroup$
$begingroup$
The 4 conclusion is wrong - a radii can bisect a chord and not being perpendicular
$endgroup$
– Moti
Dec 10 '18 at 5:05
$begingroup$
Thanks, what about the second video? At 3:40 he says "because EF is congruent to EG; then AB is congruent to CD", which is wrong in my opinion as EF has to be perpendicular to AB and EG has to be perpendicular to CD in order to say that AB is congruent to CD. Correct me if I'm wrong.
$endgroup$
– Jak
Dec 10 '18 at 9:28
$begingroup$
EF and EG are congruent and perpendicular as defined by distance. Than you prove that AB is congruent (=) to CD based on SAS (one of the sides is the radii of the circle. It is not clear what the guy tries to prove with the drawings.
$endgroup$
– Moti
Dec 13 '18 at 8:03
$begingroup$
I basically mean the sentence that starts at 3:30 is incorrect "You need to know that if 2 chords of a circle are equidistant from the centre, then they are congruent".
$endgroup$
– Jak
Dec 14 '18 at 9:40
$begingroup$
This statement is true and can be proven.
$endgroup$
– Moti
Dec 15 '18 at 0:50
|
show 2 more comments
$begingroup$
I've been revising some geometry theorems, watching YouTube videos made by @The Organic Chemistry Tutor. I found 2 issues, which I'm not sure about.
in first video
The proof starts at 5:40. In step 4, in the column proof (at 6:54) he says that segment BD is perpendicular to segment AC. I don't understand how come, assuming all we know are the givens in the example, bisector BD doesn't have to be perpendicular, or am I wrong?
in second video
It starts at 2:50. He says "You need to know that if 2 chords od a circle are equidistant from the centre, then they are congruent". and then "Because segment EF is congruent to segment EG, then chord AB is congruent to CD" I thought that EF has to be perpendicular to AB and EG has to be perpendicular to CD to say that the chords AB and CD are congruent, or am I wrong?
I'm a bit confused, as both videos have many likes, so I think I might be wrong. Thanks in advance for correcting me if I'm wrong.
geometry
asked Dec 9 '18 at 22:28
JakJak
274
$endgroup$
I've been revising some geometry theorems, watching YouTube videos made by @The Organic Chemistry Tutor. I found 2 issues, which I'm not sure about.
in first video
The proof starts at 5:40. In step 4, in the column proof (at 6:54) he says that segment BD is perpendicular to segment AC. I don't understand how come, assuming all we know are the givens in the example, bisector BD doesn't have to be perpendicular, or am I wrong?
in second video
It starts at 2:50. He says "You need to know that if 2 chords od a circle are equidistant from the centre, then they are congruent". and then "Because segment EF is congruent to segment EG, then chord AB is congruent to CD" I thought that EF has to be perpendicular to AB and EG has to be perpendicular to CD to say that the chords AB and CD are congruent, or am I wrong?
I'm a bit confused, as both videos have many likes, so I think I might be wrong. Thanks in advance for correcting me if I'm wrong.
geometry
geometry
asked Dec 9 '18 at 22:28
JakJak
274
asked Dec 9 '18 at 22:28
JakJak
274
asked Dec 9 '18 at 22:28
JakJak
274
asked Dec 9 '18 at 22:28
JakJak
274
asked Dec 9 '18 at 22:28
JakJak
274
274
$begingroup$
The 4 conclusion is wrong - a radii can bisect a chord and not being perpendicular
$endgroup$
– Moti
Dec 10 '18 at 5:05
$begingroup$
Thanks, what about the second video? At 3:40 he says "because EF is congruent to EG; then AB is congruent to CD", which is wrong in my opinion as EF has to be perpendicular to AB and EG has to be perpendicular to CD in order to say that AB is congruent to CD. Correct me if I'm wrong.
$endgroup$
– Jak
Dec 10 '18 at 9:28
$begingroup$
EF and EG are congruent and perpendicular as defined by distance. Than you prove that AB is congruent (=) to CD based on SAS (one of the sides is the radii of the circle. It is not clear what the guy tries to prove with the drawings.
$endgroup$
– Moti
Dec 13 '18 at 8:03
$begingroup$
I basically mean the sentence that starts at 3:30 is incorrect "You need to know that if 2 chords of a circle are equidistant from the centre, then they are congruent".
$endgroup$
– Jak
Dec 14 '18 at 9:40
$begingroup$
This statement is true and can be proven.
$endgroup$
– Moti
Dec 15 '18 at 0:50
|
show 2 more comments
$begingroup$
The 4 conclusion is wrong - a radii can bisect a chord and not being perpendicular
$endgroup$
– Moti
Dec 10 '18 at 5:05
$begingroup$
Thanks, what about the second video? At 3:40 he says "because EF is congruent to EG; then AB is congruent to CD", which is wrong in my opinion as EF has to be perpendicular to AB and EG has to be perpendicular to CD in order to say that AB is congruent to CD. Correct me if I'm wrong.
$endgroup$
– Jak
Dec 10 '18 at 9:28
$begingroup$
EF and EG are congruent and perpendicular as defined by distance. Than you prove that AB is congruent (=) to CD based on SAS (one of the sides is the radii of the circle. It is not clear what the guy tries to prove with the drawings.
$endgroup$
– Moti
Dec 13 '18 at 8:03
$begingroup$
I basically mean the sentence that starts at 3:30 is incorrect "You need to know that if 2 chords of a circle are equidistant from the centre, then they are congruent".
$endgroup$
– Jak
Dec 14 '18 at 9:40
$begingroup$
This statement is true and can be proven.
$endgroup$
– Moti
Dec 15 '18 at 0:50
$begingroup$
The 4 conclusion is wrong - a radii can bisect a chord and not being perpendicular
$endgroup$
– Moti
Dec 10 '18 at 5:05
$begingroup$
The 4 conclusion is wrong - a radii can bisect a chord and not being perpendicular
$endgroup$
– Moti
Dec 10 '18 at 5:05
$begingroup$
Thanks, what about the second video? At 3:40 he says "because EF is congruent to EG; then AB is congruent to CD", which is wrong in my opinion as EF has to be perpendicular to AB and EG has to be perpendicular to CD in order to say that AB is congruent to CD. Correct me if I'm wrong.
$endgroup$
– Jak
Dec 10 '18 at 9:28
$begingroup$
Thanks, what about the second video? At 3:40 he says "because EF is congruent to EG; then AB is congruent to CD", which is wrong in my opinion as EF has to be perpendicular to AB and EG has to be perpendicular to CD in order to say that AB is congruent to CD. Correct me if I'm wrong.
$endgroup$
– Jak
Dec 10 '18 at 9:28
$begingroup$
EF and EG are congruent and perpendicular as defined by distance. Than you prove that AB is congruent (=) to CD based on SAS (one of the sides is the radii of the circle. It is not clear what the guy tries to prove with the drawings.
$endgroup$
– Moti
Dec 13 '18 at 8:03
$begingroup$
EF and EG are congruent and perpendicular as defined by distance. Than you prove that AB is congruent (=) to CD based on SAS (one of the sides is the radii of the circle. It is not clear what the guy tries to prove with the drawings.
$endgroup$
– Moti
Dec 13 '18 at 8:03
$begingroup$
I basically mean the sentence that starts at 3:30 is incorrect "You need to know that if 2 chords of a circle are equidistant from the centre, then they are congruent".
$endgroup$
– Jak
Dec 14 '18 at 9:40
$begingroup$
I basically mean the sentence that starts at 3:30 is incorrect "You need to know that if 2 chords of a circle are equidistant from the centre, then they are congruent".
$endgroup$
– Jak
Dec 14 '18 at 9:40
$begingroup$
This statement is true and can be proven.
$endgroup$
– Moti
Dec 15 '18 at 0:50
$begingroup$
This statement is true and can be proven.
$endgroup$
– Moti
Dec 15 '18 at 0:50
|
show 2 more comments
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$begingroup$
The 4 conclusion is wrong - a radii can bisect a chord and not being perpendicular
$endgroup$
– Moti
Dec 10 '18 at 5:05
$begingroup$
Thanks, what about the second video? At 3:40 he says "because EF is congruent to EG; then AB is congruent to CD", which is wrong in my opinion as EF has to be perpendicular to AB and EG has to be perpendicular to CD in order to say that AB is congruent to CD. Correct me if I'm wrong.
$endgroup$
– Jak
Dec 10 '18 at 9:28
$begingroup$
EF and EG are congruent and perpendicular as defined by distance. Than you prove that AB is congruent (=) to CD based on SAS (one of the sides is the radii of the circle. It is not clear what the guy tries to prove with the drawings.
$endgroup$
– Moti
Dec 13 '18 at 8:03
$begingroup$
I basically mean the sentence that starts at 3:30 is incorrect "You need to know that if 2 chords of a circle are equidistant from the centre, then they are congruent".
$endgroup$
– Jak
Dec 14 '18 at 9:40
$begingroup$
This statement is true and can be proven.
$endgroup$
– Moti
Dec 15 '18 at 0:50