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math question =S

haochen

haochen

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in b) ii) they ask only one faulty so there are two path to get this answer .
"Faulty then Not faulty" or "not faulty then faulty" (because u only nedd one faulty)
so we use the "Or" rule (add) (becoz u can take either one)
(1/20 * 19/20) + (19/20 * 1/20) (if u solve the previous one u shud now it :) )
19/400 + 19/400
= 38/400

hope u got it :D
 
Aahmsil

Aahmsil

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Answer

Look at the image of the diagram.

diagrams.html


Note: If you can't see the image of the diagram and it just appears as a small box, right click on the box and press 'open in new tab'/'open in new window'.

Or just click on this link: http://wazzaaap.weebly.com/diagrams.html

First off, notice that if you join the dots (the dots are the centres of the trunks) with lines, an equilateral triangle is formed. This can be proved by calculating the lengths of each side; 31 cm [radius] x 3 = 93 for each side. This being the case, if the curved edges of the plastic sheet are extended with straight lines, we can assume that this too will form an equilateral triangle.

We begin by drawing two tangents to the circle at the bottom left corner of the diagram (since the question asks about this).

Observe that the two dotted lines in the question along with the tangents that we've drawn now form a quadrilateral.


The red angles are calculated as follows:
180 - 90 = 90 (angles on a straight line)

The yellow angle is 60 since it is an interior angle of an equilateral triangle. An equilateral triangle always has interior angles each of 60 because; 180/3 = 60 (all angles in such a triangle are equal).

We can therefore use the angles we've found to calculate angle ECD;
360 = (90 x 2) + 60 + ECD (interior angles of a quadrilateral add up to 360)
360 = 240 + ECD
ECD = 360 - 240
ECD = 60

Cheers !!! :D

Hope that was helpful and not too late !!! :D
 
Aahmsil

Aahmsil

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Diagram issue

If you can't see the image of the diagram and it just appears as a small box, right click on the box and press 'open in new tab'/'open in new window'.

Cheers !!! :D
 
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