Maths

2008-08-12 9:45 pm
1.(a) In the figure , a paper cylinder of basic diameter 6cm and height 8cm is cut along AB to form a piece of paper of dimensions x cm x w cm

(b) Find w ,correct to 2 decimal places.

2. In the figure AD⊥BC and D is the mid-point ob BC . Prove that △ABC is isosceles.

回答 (1)

2008-08-12 10:02 pm
✔ 最佳答案
2.
AD⊥BC , angle ADB = angle ADC = 90degree
BD = DC (D is the mid-point ob BC )
AD = AD (common side)
triangle ADB = triangle ADC (SAS)
angle ABC = angle ACB (corresponding angles)
△ABC is isosceles (base angles equal)

2008-08-12 14:06:08 補充:
1.
basic diameter 6cm means radius = 3cm
the circumfrence of the paper cylinder becomes the width of the paper after cutting
the width :
2pi(3)
= 6picm
= 18.85cm(corr. to 2 dec.places)


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