Mathematics: Post your doubts here!

[TheJDOG]

NO.6 anyone ?
P3 mathematics

Hello Paresh.

Q6) I)First off, were told that perimeter of shade= 1/2 circle circumference
Find radius of shade by dropping down a perpendicular so you get this in terms of r and x. Also theta here will be 2x. Radius of shade we do cosx= Adj/r , hence adj = rcosx and so side AB= 2rcosx
Also side AC is 2rcosx
So Perimeter Shade= 1/2 Circle Circumference Get arc length = rtheta = 2rcosx 2x= 4rxcosx
Arc + AB + AC= 1/2 x 2pier
4rxcosx + 2rcosx + 2rcosx= pier
Cross r
4xcosx + 4cosx = pie Notice on left hand side cosx is a common factor

So cosx(4x + 4) = pie
Cosx= pie/(4x + 4)
X = cosinverse(pie/4x+4)

Done part ii) and iii) are easy and straightforward

 

[ZaqZainab]

Plzz Zaq sarcastic & others... help me clear my concept.
When we are ask to find the acute angle b/w the lines/planes we need to use the formula N1 * N2= |N|*|N| cosQ/sinQ
My question is when to use SinQ and CosQ when we are using this formula to calculate the Q ?

If you use cos you will get a values which isn't the acute angle then you have to 180-(cos-1(...)) we use sin for angle between line and plan
while for angle between 2 lines of 2 planes we use sin. this is what my teacher has taught me

 

[mohammad hurani]

I need help in statistics .. I understand everything about part ii) except why did they multiply the area by 2 ?

 

[m7aug]

please help, can any anybody please show me how to solve part 1 in the image below?

 

[papajohn]

please help, can any anybody please show me how to solve part 1 in the image below?

I`m solving wait

 

[papajohn]

please help, can any anybody please show me how to solve part 1 in the image below?

Here yew goooo

 

[Gehad Mohamed]

Hello
Please help me solve last part of this question

W10 / 33

 

[Bilal Khan]

maxpapers.com/wp-content/uploads/2012/11/9709_s13_ms_32.pdf

Can someone solve question 9 part b ?
Can't find greatest value of z mod.

 

[sara kamal]

please specify which part?

Full Question.thank you

 

[sumi]

Can someone please solve these questions with working (thanking you in advance)
1. The average of seven numbers is 12, and the average of three of them is –11. What is the sum of the other four numbers?
A 33 B 63 C 84 D 117

2. The price of a TV in 1970 increased by 300% in 1980. The price of the 1980 model TV increased by 200% in 1990. By what percentage did the price increase from 1970 to 1990?
A 500% B 600% C 900% D 1100%

 

[qwertypoiu]

Can someone please solve these questions with working (thanking you in advance)
1. The average of seven numbers is 12, and the average of three of them is –11. What is the sum of the other four numbers?
A 33 B 63 C 84 D 117

2. The price of a TV in 1970 increased by 300% in 1980. The price of the 1980 model TV increased by 200% in 1990. By what percentage did the price increase from 1970 to 1990?
A 500% B 600% C 900% D 1100%

Sum of 7 numbers = 7*12=84
Sum of three of them=3*-11=-33
Sum of other four = 84-(-33)=117

2.
If price increases by 300%, the price has become four times the previous price. If then it increases by 200%, price has become three times previous. So overall, price is 4*3=12 times of original. That means price increased by 1100%

This does not seem A level to me BTW

 

[phanttasy]

So today I bought a photostat version or this but found out that there was no answer behind! Does anyone know where can I find the solutions for this book? p/s: this is a practice book, it's not a test book

 

[Muhaka2015]

Pls help on 2012 p3/33 q 10 this is my first question

 

[TheJDOG]

Pls help on 2012 p3/33 q 10 this is my first question

June or October?

 

[m7aug]

Here yew goooo

thank you very much

 

[ashcull14]

WEIGHT OF B??? can someone explain by resolving forces on B on diagram ????????

 

[TheJDOG]

View attachment 52123
WEIGHT OF B??? can someone explain by resolving forces on B on diagram ????????

Let's get weight of B shall we?
First off, extend the arrow of the 18 N force on B, you will see that its angle between it and the horizontal is also 30!
We know B is in equilibrium also, so take axis directly on the smooth plane. Notice no friction here it's smooth.
R(->) resolve on x axis 18cos30= Wsin30
So W= 18root3= 31.18 N

Note I can draw it for you and attach the picture here but how do I do that?

 

[ashcull14]

in part 1 i used v=u+at but the ans turned out to be wrong why??
i used vP= 1.3 +(0.1*20)=3.3m/s
ince vP=vQ so 3.3= vQ
thus, at t=20s 3.3= uQ+(0.016*20) uQ= 3.3-0.32=2.98m/s
Whereas, in markscheme the formula s=ut+1/2at^2 is used which gives the ans 0.1m/s
Can someone explain why cant we use v=u+at here???

 

[ashcull14]

Let's get weight of B shall we?
First off, extend the arrow of the 18 N force on B, you will see that its angle between it and the horizontal is also 30!
We know B is in equilibrium also, so take axis directly on the smooth plane. Notice no friction here it's smooth.
R(->) resolve on x axis 18cos30= Wsin30
So W= 18root3= 31.18 N

Note I can draw it for you and attach the picture here but how do I do that?

u can attach a picture by clicking the option 'upload a file and open the pic from your library

 

[TheJDOG]

u can attach a picture by clicking the option 'upload a file and open the pic from your library

Here you go