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primary 5 | Maths
| Angles & Geometry
One Answer Below
Anyone can contribute an answer, even non-tutors.
Pls assist. Tks
Date Posted: 6 years ago
Views: 920
The answer of 23 degrees is correct.
Hi Phylicia, that's great!
Just a note, be careful that your concept of ∠ACB=∠ACD is incorrect ∠ACB and ∠ACD cannot be assumed to be the same even though triangle BCD is an isosceles. Please note! :)
Triangle BCD is an isosceles, that means that BC = CD and ∠DBC = ∠BDC only!
After looking, try working it out. It helps!
Cheers,
Ivan
Just a note, be careful that your concept of ∠ACB=∠ACD is incorrect ∠ACB and ∠ACD cannot be assumed to be the same even though triangle BCD is an isosceles. Please note! :)
Triangle BCD is an isosceles, that means that BC = CD and ∠DBC = ∠BDC only!
After looking, try working it out. It helps!
Cheers,
Ivan
Haha Ivan, can perceive you are very enthusiastic. I tutor secondary sch maths so this is a cinch ;)
@Phylicia: Oh hey! I mistook you for the original poster, Mandy. So you teach too. Where're you from?
See 1 Answer
Just a note, be careful that your concept of ∠ACB=∠ACD is incorrect Please note! :)
Triangle BCD is an isosceles, that means that BC = CD and ∠DBC = ∠BDC only!
Triangle BCD is an isosceles, that means that BC = CD and ∠DBC = ∠BDC only!
I'm sorry @Ms Jaslyn Lim, but your answer ∠BDC = 53 degrees is not correct.
We know that triangle ACB is an equilateral triangle, i.e. AB= AC= BC and triangle BCD is an isosceles triangle, i.e. BC=CD.
Hence we know that AC = CD. That is, ACD is an isosceles triangle (triangle with two equal sides is ALWAYS an isosceles). i.e. ∠DAC = ∠ADC = 53 degrees.
Hence ∠ACD = 180-53-53=74 degrees.
∠DBC = BDC = (180-60-74)/2=23 degrees.
I have mathematical proofing for my answer. Can you show proof for your answer?
We know that triangle ACB is an equilateral triangle, i.e. AB= AC= BC and triangle BCD is an isosceles triangle, i.e. BC=CD.
Hence we know that AC = CD. That is, ACD is an isosceles triangle (triangle with two equal sides is ALWAYS an isosceles). i.e. ∠DAC = ∠ADC = 53 degrees.
Hence ∠ACD = 180-53-53=74 degrees.
∠DBC = BDC = (180-60-74)/2=23 degrees.
I have mathematical proofing for my answer. Can you show proof for your answer?
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