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primary 5 | Maths
| Angles & Geometry

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Pls assist. Tks

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

### See 1 Answer

Triangle BCD is an isosceles, that means that BC = CD and ∠DBC = ∠BDC only!

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?