Mathematics: Post your doubts here!

[Thought blocker]

I'd appreciate it ..

a)
f(x) = 4 - 3 sin x = 2
-3 sin x = -2
sin x = 2/3
x ≈ 0.7297276562... ≈ 0.73

b)
1 ≤ sin x ≤ 1
-3 ≤ 3 sin x ≤ 3
3 ≥ -3 sin x ≥ -3
7 ≥ 4 - 3 sin x ≥ 1

If k < 1 or k > 7, there is no solution.

c)
A = 3π/2

d)
g(x) = 4 - 3 sin x = y
4 - 3 sin y = x
4 - x = 3 sin y
(4 - x)/3 = sin y
sin^-1 (4 - x)/3 = y= g^-1

e)
g^-1 (3) = sin^-1 (4 - 3)/4 = sin^-1 1/4 = 2.8017557... ≈ 2.802

 

[sudeep1097]

http://onlineexamhelp.com/wp-content/uploads/2014/02/9709_w13_qp_32.pdf

Q3

somebody please solve it out like all the steps... i did it but i don't get what they want in the ms and i can't get the exact answer on my own... got an answer in decimals but dont even know if thats correct... helpss :')

I haven't checked the markscheme but I am pretty sure this is the answer!

 

[Thought blocker]

hi everyone, i can't seem to solve this right :/

In mechanical physics the word "threaded" means some kind of thread engagement.
In this question "threaded" simply means that the roughly surfaced rod is inserted into the ring. Here a "common meaning" but not the technical meaning of the word "threaded" is used. I object to such use in physics which is where technical meanings should be given and learned.

To me the 3rd Law of Newton should be the answer to the question. That is, the force of rod on ring should equal 2 N in a direction that is 180° opposite to that shown in diagram.

Suchal Riaz ZaqZainab midha.ch

 

[Thought blocker]

I haven't checked the markscheme but I am pretty sure this is the answer!

Is p3 hard ??

 

[sudeep1097]

Not that much integration and differentiation have become more difficult but with practice it will be a breeze. Complex numbers and Vectors are challenging and to be honest I really hate vectors. But still p3 easier than other subjects for me

 

[Thought blocker]

In mechanical physics the word "threaded" means some kind of thread engagement.
In this question "threaded" simply means that the roughly surfaced rod is inserted into the ring. Here a "common meaning" but not the technical meaning of the word "threaded" is used. I object to such use in physics which is where technical meanings should be given and learned.

To me the 3rd Law of Newton should be the answer to the question. That is, the force of rod on ring should equal 2 N in a direction that is 180° opposite to that shown in diagram.

Suchal Riaz ZaqZainab midha.ch

I took help from yahoo, but still confused help please to me and sudeep1097

 

[daredevil]

I haven't checked the markscheme but I am pretty sure this is the answer!

yeah well ur answer is ryt and i did the same stuff except that i was confused at the point that...

ln4^4 = 4ln4 right?? from the log rules??

so how can ln4 x 4 be the same thing???

 

[sudeep1097]

yeah well ur answer is ryt and i did the same stuff except that i was confused at the point that...

ln4^4 = 4ln4 right?? from the log rules??

so how can ln4 x 4 be the same thing???

It is the same thing ln4 x 4 = 4ln4 = ln4^4. It's all the same no worries

 

[abruzzi]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w12_qp_31.pdf
Please help me understand the solution for qn no. 5(iii). I just can't solve it.
Thanks

 

[Suchal Riaz]

hi everyone, i can't seem to solve this right :/

I took help from yahoo, but still confused help please to me and sudeep1097

don't make the things overly complicated.
the ring is in equilibrium. so the resultant of force is zero. it means that the force exerted by ring on rod is equal and opposite to F. let R be force exerted by ring. here i am assuming that friction is a component of the force R.
on string then ||R|| = 2 N
direction = -120degree from horizontal or 240 degrees from horizontal or 120 degree anticlockwise from rod.

 

[Thought blocker]

don't make the things overly complicated.
the ring is in equilibrium. so the resultant of force is zero. it means that the force exerted by ring on rod is equal and opposite to F. let R be force exerted by ring. here i am assuming that friction is a component of the force R.
on string then ||R|| = 2 N
direction = -120degree from horizontal or 240 degrees from horizontal or 120 degree anticlockwise from rod.

ty

 

[salvatore]

Sorry I was feeling bored to solve part ii that time haha.
OK now,
substituting value of z and simplifying you get. 1 /(2cosθ+2)-2sinθ i
Multiplying by it's conjugate i.e. (2cosθ +2)+2sinθ i and again simplifying we get,
(2cosθ +2+2sinθ i) / 4cos^2θ + 8cosθ + 4 + 4sin^2θ
=numerator/ 8+8cosθ [4cos^2θ + 4sin^2θ = 4]
Now separating the real part only from numerator 2(cosθ +1) / 8(cosθ +1)
Hence real part = 1/4

Thanks man.. much appreciated

 

[Suchal Riaz]

Thought blocker here are definition of
"thread"(verb):
1- pass (a long, thin object or piece of material) through something and into the required position for use. (used in this question)
2- put (beads or other small objects) on a thread, chain, etc. (what you said)
3- cut a screw thread in or on (a hole, screw, or other object).(irrelevant to math questions)

 

[Namehere]

NOONE IS ANSWERING ME THIS QUESTION AND I REALLY NEED AN EXPLANATION FOR IT (HENCE THE CAPS).
Its Q8(b), I get the diagram part, but dont know how to find the least value.

Thank you in advance!

 

[daredevil]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w12_qp_31.pdf
Please help me understand the solution for qn no. 5(iii). I just can't solve it.
Thanks

it is actually a progressive sort of question... take the square of RHS of identity from ii as the LHS is seen to have been squared....

 

[sitooon]

NOONE IS ANSWERING ME THIS QUESTION AND I REALLY NEED AN EXPLANATION FOR IT (HENCE THE CAPS).
Its Q8(b), I get the diagram part, but dont know how to find the least value.

Thank you in advance!

Its because no one no the answer !

 

[Thought blocker]

Thought blocker here are definition of
"thread"(verb):
1- pass (a long, thin object or piece of material) through something and into the required position for use. (used in this question)
2- put (beads or other small objects) on a thread, chain, etc. (what you said)
3- cut a screw thread in or on (a hole, screw, or other object).(irrelevant to math questions)

What was this for ?

 

[sitooon]

it is actually a progressive sort of question... take the square of RHS of identity from ii as the LHS is seen to have been squared....

For Modulus questions , i get the two values of X which the questions asks ..
however when i try to write the inequality i dont get it !
is there any rule to write the inequalty because sometimes they give ranges as ans and sometimes ... or ,,,,

 

[abruzzi]

it is actually a progressive sort of question... take the square of RHS of identity from ii as the LHS is seen to have been squared....

Thanks a lot mate.
If you don't mind, could you please help me with qn no. 8(ii) of the same paper? Sorry for bothering..

 

[Suchal Riaz]

In mechanical physics the word "threaded" means some kind of thread engagement.
In this question "threaded" simply means that the roughly surfaced rod is inserted into the ring. Here a "common meaning" but not the technical meaning of the word "threaded" is used. I object to such use in physics which is where technical meanings should be given and learned.

To me the 3rd Law of Newton should be the answer to the question. That is, the force of rod on ring should equal 2 N in a direction that is 180° opposite to that shown in diagram.

Suchal Riaz ZaqZainab midha.ch

For this.