# Maths URGENT HELP Plz

#### XPFMember

XPRS Moderator
bamteck said:
Plz Plz Help ::
What difficulty do u have??
(i) 6
(ii) (a)Area of circle is nr^2....the diameter of the largecircles is equal to the 3 diameters of small circle .....hence find the radius...and then find the area!!
(b) find the total area of small circles ...find the difference b/w large circle area and total area of small ones!!this gives the left out part...if u notice there are 6 such regions similar to shaded one so if u divide the difference by 6 u will get the shaded area i think u might be finding this part difficult!! hope u r clear with it now...i did nt give u the answer cuz u shud try it on ur own!!I can help u but its always better to it urself #### XPFMember

XPRS Moderator
bamteck said:
For this one, I need only to know the (a) (iii) the shortest distance from C to BD

& part (b) The greatest angle of depression..

Plzzzzz
Remember...the shortest distannce is always the perpendicular distance!!
so then u can use the trignometric ratios....in this case sin0 = opp/hyp...and find opp when hyp = 1040 and 0= 42 degrees!!

#### abcde

Rightly said math angel! As for the next question bamteck,
the shortest distance from C to BD is the perp. distance from C to BD. Since u knowangle CBD and BC, the answer would be: sin 42= x/1040.
The greatest angle of depression would occur where the perpendicular distance from C to BD is shortest. So tan x =500/perp. distance found in (a) (iii).
Hope this helps #### bamteck

Thanks Maths angel, Yea i'm going to try it out. I'll let u know in a while !

#### bamteck

Thnx abcde.. I have exams on thursday, n i'm working all the exam papers to achieve a good credit !

#### abcde

Good to know that !Do you have Mathematics D exam or Add-maths exam?

#### bamteck

Well, I do mathematics, the syllabus D..

For add maths, I do the 4037 !

Are u good in maths also?

#### abcde

I am also appearing in add-maths this session! How are you preparing for it?

#### bamteck

Well I'm just working all past papers !

This gonna help.

#### UxaiR

for the (d) part

total volume = 2 (pie) (r) (h) x 1.5
500 = 2(pie) (r) (6) x 1.5

from here you can get (r) value Fnx dude.

#### XPFMember

XPRS Moderator
I suppose the question to be done in this way:
vol.of hollow cylinder = (pi) x h x (R^2 - r^2)
Where R is the radius of big circle and r is the radius of small circle.....so R = r + 1.5
since we know vol. as 500...R=1.5 + r .....h = 6 solve the equation!!

500 = (pi) x 6 x [(1.5 + r)^2 - r^2]

500/[6(pi)] = r^2 + 3r + 2.25 - r^2
500/[6(pi)] = 3r + 2.25

r = 8.0919 = 8.09

Note...(r + 1.5 ) ^2 = r^2 + 3r + 2.25 ....[recall expanding (a + b)^2

Actually i havent understand what Uxair has done...but i'm quite sure my answer and method is correct!!

#### XPFMember

XPRS Moderator
The questions nt clear by the right side...pla post it again!!

#### XPFMember

XPRS Moderator
it's quite easy...for c u have to plot the points given in the grid above...for d just draw a tangent to the curve at the given point....and find the gradient of the line......for e (i) draw the line when the eqn of line is what is given....(by plotting the grid)
(ii) then write the point where te line intersects the graph....
(iii) equate both the eqns. ....the eqn of curve = 1/2 x + 3
and simpligy to make it in the form required...
hope u understood #### bamteck

Sorry, I did not understand.. 