I am looking for Books or Websites with worked out examples , Not sure which book to look at ?

Please help

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Sorry, English is not my mother tongue!

Agnishom wrote:

]]>How many different sandwiches can we make?

I think you want to ask "In how many ways can we make these system of 3 sandwiches while satisfying the constraints?"

I hope this diagram will help you.

If the lines are AB and CD and they are both in the same (2 dimensional) plane, then they must cross (when not parallel). When parallel the distance between them is constant but if not parallel then the distance between will vary and can be zero. This means they cross. In this case the answer is 1 point.

In 3 dimensions it is possible for the lines to be 'skew'. Skew lines are not parallel but do not cross. In the diagram AB and EF are a pair of skew lines. AB is confined to the top plane and EF cuts that plane once at F, so these lines never cross. Number of points is then zero.

If the 'two' lines are, in fact, just a single line then they 'cross' everywhere, so they would have an infinity of crossing points. But two lines that are the same line are considered to be parallel, so infinity will never be an answer.

Bob

]]>LuisRodg wrote:Theres actually a formula to figuring out the sum of the angles of a polygon:

180(n-2) where n is the sides of the polygon.

Which I see he/she used by doing 180(5-2) = 540.

yea, but he wanted to know why

Well, I have tried to prove that, using sectors of a circle. Make a circle, then divide it to five equal sectors. After that, make a regular pentagon inside the circle. Each sector will have 72° as their radius angle. From this, you can know that each angle of the pentagon is 108°. Multiplying it by 5 will give 540°. You can do for other polygons to get similar proof.

]]>Thanks anyway!]]>

It looks like this is a binomial probability question. http://www.mathsisfun.com/data/binomial … ution.html

If p is the probability of one network working, then the probability of exactly M working out of N is

where

But you would also be happy if more than M are working so you need to add up all Ps from M up to N:

Hope that's what you wanted.

Bob

]]>Welcome to the forum.

Your problem has been posted before (and answered).

http://www.mathisfunforum.com/viewtopic.php?id=23062

Bob

]]>In geometry you always have to be careful not to assume some property just because it looks like it's true. In that diagram you're not told that BDC = 90 or alternatively that BD is parallel to AE. If either is true then all the triangles are 30-60-90, but if you shift point D a little along CF then triangle BDC isn't 30-60-90 any longer.

Bob

]]>MisterMaths wrote:I was to determine whether this sequence is convergent or divergent: Un=http://i.imgur.com/BOwr53L.png

That sequence is convergent.

As n approaches infinity, each expression on either side of the subtraction sign approaches 1. That answers the part of convergence/the question.

I know it is convergent, the problem lies within proving it is convergent.

]]>17) 14

18) 5

19) 20

20) 1

]]>Welcome to the forum.

In trigonometry, Sin of any angle of a right-angled triangle is the Opposite over the hypotenuse,

cos of any angle is the adjacent over the hypotenuse and

the tan of any angle is opposite over the adjacent.

Cosec is the inverse of sine function i.e. cosec of any angle is hypotenuse over opposite,

Sec is the inverse of cosine function i.e. sec of any angle is hypotenuse over adjacent and

cot is the inverse of tan i.e. adjacent over opposite.

So, in this figure:

sin x=4/5

cos x=3/5

tan x=4/3

cosec x=5/4

sec x=5/3

cot x=3/4

Similarly you can do that for the above angle. I leave that to you. Hope you can do.

In the next question,

The angle adjacent to base( which we generally call "theta"θ) is given and the base is given and you need to find the perpendicular. Its as easy as that.

15.θ=71°

b=20 m

p=?

tanθ=p/b

⇒tanθ*b=p

⇒tan(71°)*20=p

⇒2.904(20)=p

⇒58.08=p

So the height of the building is 58.08 m.

I hope you can do the rest.

For more information on trigonemetry visit:http://www.mathsisfun.com/algebra/trigo … index.html

or for video lessons you may watch Khan Academy's playlist of trigonemtry:https://www.youtube.com/watch?v=Jsiy4Tx … C1DBF770E7

Hope it helps

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