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primary 6 | Maths | Measurement
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Joel Su
Joel Su

primary 6 chevron_right Maths chevron_right Measurement chevron_right Singapore

I cant find B

Date Posted: 4 years ago
Views: 239
meemaw
Meemaw
4 years ago
since AB is parallel to DC,
angle BDC=42
triangle BDC is an isosceles triangle, angle DBC = (180-42) ÷ 2
angle ADB = angle DBC = 69
angle ADC= 69+42=111
angle BAD = 180-111=69
angle FAB = 180-69=111
J
J
4 years ago
But AD is not parallel to BC.

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Hope this could help
J
J
4 years ago
i)

You got the isosceles triangle's base angles mixed up. Those are not the base angles.

BD = CD, not BC = BD

ii)

You've used the wrong pair of lines for the justification of the alternate angles.

Besides that the other pair of lines , (ADand BC), aren't parallel since the question did not specify and it cannot be deduced from the info also.
Joel Su
Joel Su
4 years ago
So this (b) is not solvable right?
J
J
4 years ago
You might have to assume ∠FDB is 90°. I've seen this question in some past year paper and the answer key took it to be 90° as well.
Joel Su
Joel Su
4 years ago
That’s way at the answer says. But that’s not correct to assume anything without proof.
J
J
4 years ago
My guess is that the setters omitted the right angle marking by mistake.

Turns out this question is from MGS 2019 SA1.

If you're doing this as a practice paper on your own, you may skip part b) , or contact the school for clarification.

If you're doing this as question given by your school then it's best to ask your teachers .