Paper2_Math_D_Jun2005

Pls see my comment.

Q1c(ii) You should have scored full marks for this Q. You have
derived the equation but you forgot to express the values
of x=+5,-5

Q3b Technique : Remember the value of the interior angles of
(a) 4 sided shape eg rectangle is 360 deg (b) 5 sided
pentagon is 540 deg (c)6 sided hexagon is 720 deg.
I hope you know how to explain the above. A rectangle
contains 2 triangles, thus their interior angles is equal
to 180x2 = 360 deg.
Note the Q said that the hexagon has rotational symmetry
of order 3. It just mean that each of the 3 mini hexagon
inside the big hexagon are symmetry.
Given one of the interior angle is 105 deg, thus 2 other
interior angles of the other 2 mini hexagon are also 105
deg. Similarly there are also 3 angles with z deg.
Thus (3*105)+3z=720; z=(720-315)/3=135 deg
This is a technique you must remember.

Q3c Pls check whether there are formulae for similar triangle.

Q4c You must first know what is the path? A straight line or
an arc of a circle? In this case it is an arc of a circle
with angle ACA’=125 deg.
Thus 125/360 * 2pi(r) = (125/360)*2*22/7*20=43.6 cm

Q7d Vol of the outer cylinder–Vol of inner cylinder = 500 cm3
Let radius of inner cylinder = r cm
Radius of outer cylinder = r + 1.5 cm

Q8b(i) Your answer -0.50 is quite near -0.44. Did you round up?

Q9 Pls check whether there are formulae for such triangles
which are not right angle triangles

Q11(i) Pls check again.
Q11(iv) Pls check again. You are quite ok with this chapter.
Maybe you careless here.