Regent College
Maths Department
Core Mathematics 4
Trapezium Rule
C4 Integration
Page 1
Integration
It might appear to be a bit obvious but you must remember all of your C3
work on differentiation if you are to succeed with this unit.
Content
Use of trapezium rule to provide approximate solution to integrals.
C4 Integration
Page 2
Standard Integrals
Function (f(x))
Integral  f(x)dx
xn
xn 1
c
n 1
ln x  c
1
x
(ax + b)n
1
ax  b
ex
Sin x
Cos x
Tan x
Cot x
Cosec x
Sec x
Sec2x
Sec x Tan x
-Cosec2x
eax+b
Cos (ax + b)
SinnxCosx
CosnxSinx
Sin2x
Cos2x
C4 Integration
(ax  b)n 1
c
a(n  1)
1
ln ax  b  c
a
ex + c
-Cos x + c
Sin x + c
ln|(Sec x)| + c
ln|(Sin x)| + c
-ln|(Cosec x + Cot x)| + c
ln|(Sec x + Tan x)| + c
Tanx + c
Sec x + c
Cot x + c
e ax b
c
a
1
Sin(ax  b)  c
a
 1 
n 1

 Sin x  c
n

1


 1 
n 1

 C os x  c
n 1
1
Sin 2x 
x 
c

2
2 
1 Sin 2x

 x c

2 2

Page 3
Example 1
The diagram below is the graph of the function y = Sec x
Use the trapezium rule with five equally spaced ordinates to estimate
the area of the region bounded by the curve with equation y = sec x, the


x-axis and the lines x = - and x = , giving your answer to two decimal
3
places.
3
π π
π
π
,
,0, and . The best way to
3
6
6
3
succeed with these questions is to put the information into a table.
The five x coordinates are
x
π
3
π
6
0
π
6
π
3
Y
2
1.155
1
1.155
2
Trapezium rule is introduced in AS.

b
a
π
3
π
3

f(x)dx 
1
 h  xo  2  (x1  x2  x3  ...xn  1 )  xn 
2
Secxdx 
1 π
 2  2  1.155  2  1  2  1.155  2
2 6
 2.78(2dp )
C4 Integration
Page 4
Past paper questions on Trapezium rule
1.
Figure 1
y
R
0
0.2
0.4
0.6
0.8
x
1
Figure 1 shows the graph of the curve with equation
x  0.
y = xe2x,
The finite region R bounded by the lines x = 1, the x-axis and the curve is shown shaded in Figure 1.
(a) Use integration to find the exact value of the area for R.
(5)
(b) Complete the table with the values of y corresponding to x = 0.4 and 0.8.
x
0
0.2
y = xe2x
0
0.29836
0.4
0.6
1.99207
0.8
1
7.38906
(1)
(c) Use the trapezium rule with all the values in the table to find an approximate value for this
area, giving your answer to 4 significant figures.
(4)
(C4, June 2005 Q5)
C4 Integration
Page 5
2.
(a) Given that y = sec x, complete the table with the values of y corresponding to x =

.
4
x
0
y
1

16

8
 
,
and
16 8

3
16
4
1.20269
(2)
(b) Use the trapezium rule, with all the values for y in the completed table, to obtain an estimate

4
for  sec x dx . Show all the steps of your working and give your answer to 4 decimal places.
0
(3)

4
The exact value of  sec x dx is ln (1 + 2).
0
(c) Calculate the % error in using the estimate you obtained in part (b).
(2)
(C4, Jan 2006 Q2)
3.
Figure 3
y
O
1
x
Figure 3 shows a sketch of the curve with equation y = (x – 1) ln x, x > 0.
(a) Copy and complete the table with the values of y corresponding to x = 1.5 and x = 2.5.
C4 Integration
Page 6
x
1
y
0
1.5
2
2.5
3
ln 2
2 ln 3
(1)
3

Given that I =  ( x  1) ln x dx ,
1
(b) use the trapezium rule
(i) with values at y at x = 1, 2 and 3 to find an approximate value for I to 4 significant figures,
(ii) with values at y at x = 1, 1.5, 2, 2.5 and 3 to find another approximate value for I to
4 significant figures.
(5)
(c) Explain, with reference to Figure 3, why an increase in the number of values improves the
accuracy of the approximation.
(1)
3

(d) Show, by integration, that the exact value of  ( x  1) ln x dx is
1
3
2
ln 3.
(6)
(C4, June 2006 Q6)
5

I =  e  (3 x 1) dx .
0
4.
(a) Given that y = e(3x + 1), copy and complete the table with the values of y corresponding to x = 2,
3 and 4.
x
0
1
y
e1
e2
2
3
4
5
e4
(2)
(b) Use the trapezium rule, with all the values of y in the completed table, to obtain an estimate
for the original integral I, giving your answer to 4 significant figures.
(3)
b

(c) Use the substitution t = (3x + 1) to show that I may be expressed as  kte t dt , giving the
a
values of a, b and k.
(5)
(d) Use integration by parts to evaluate this integral, and hence find the value of I correct to
4 significant figures, showing all the steps in your working.
(5)
(C4, Jan 2007 Q8)
5.
C4 Integration
Page 7
Figure 1
Figure 1 shows part of the curve with equation y = (tan x). The finite region R, which is bounded
by the curve, the x-axis and the line x =

4
, is shown shaded in Figure 1.
(a) Given that y = (tan x), copy and complete the table with the values of y corresponding to
 
3
x=
,
and
, giving your answers to 5 decimal places.
16 8
16
x
0
y
0

16

8
3
16

4
1
(3)
(b) Use the trapezium rule with all the values of y in the completed table to obtain an estimate for
the area of the shaded region R, giving your answer to 4 decimal places.
(4)
The region R is rotated through 2 radians around the x-axis to generate a solid of revolution.
(c) Use integration to find an exact value for the volume of the solid generated.
(4)
(C4, June 2007 Q7)
6.
C4 Integration
Page 8
Figure 1
The curve shown in Figure 1 has equation ex(sin x), 0  x  . The finite region R bounded by the
curve and the x-axis is shown shaded in Figure 1.
(a) Copy and complete the table below with the values of y corresponding to x =

4
and x =

,
2
giving your answers to 5 decimal places.
x
0
y
0


4
2
3
4

8.87207
0
(2)
(b) Use the trapezium rule, with all the values in the completed table, to obtain an estimate for the
area of the region R. Give your answer to 4 decimal places.
(4)
(C4, Jan 2008 Q1)
7.
C4 Integration
Page 9
Figure 1
2
Figure 1 shows part of the curve with equation y = e 0.5 x . The finite region R, shown shaded in
Figure 1, is bounded by the curve, the x-axis, the y-axis and the line x = 2.
(a) Copy and complete the table with the values of y corresponding to x = 0.8 and x = 1.6.
x
0
0.4
y
e0
e0.08
0.8
1.2
e0.72
1.6
2
e2
(1)
(b) Use the trapezium rule with all the values in the table to find an approximate value for the area
of R, giving your answer to 4 significant figures.
(3)
(C4, June 2008 Q1)
8.
C4 Integration
Page 10
Figure 1
Figure 1 shows the finite region R bounded by the x-axis, the y-axis and the curve with equation
3
x
y = 3 cos   , 0  x 
.
2
3
x
The table shows corresponding values of x and y for y = 3 cos   .
3
x
0
3
8
3
4
y
3
2.77164
2.12132
9
8
3
2
0
(a) Copy and complete the table above giving the missing value of y to 5 decimal places.
(1)
(b) Using the trapezium rule, with all the values of y from the completed table, find an
approximation for the area of R, giving your answer to 3 decimal places.
(4)
(c) Use integration to find the exact area of R.
(3)
(C4, June 2009 Q2)
9.
C4 Integration
Page 11
Figure 1
Figure 1 shows a sketch of the curve with equation y = x ln x, x  1. The finite region R, shown
shaded in Figure 1, is bounded by the curve, the x-axis and the line x = 4.
The table shows corresponding values of x and y for y = x ln x.
x
1
1.5
y
0
0.608
2
2.5
3
3.5
4
3.296
4.385
5.545
(a) Copy and complete the table with the values of y corresponding to x = 2 and x = 2.5, giving
your answers to 3 decimal places.
(2)
(b) Use the trapezium rule, with all the values of y in the completed table, to obtain an estimate
for the area of R, giving your answer to 2 decimal places.
(4)

(c) (i) Use integration by parts to find  x ln x dx .

(ii) Hence find the exact area of R, giving your answer in the form
1
(a ln 2 + b), where a
4
and b are integers.
(7)
(C4, Jan 2010 Q2)
10.
C4 Integration
Page 12
Figure 1
Figure 1 shows part of the curve with equation y = √(0.75 + cos2 x). The finite region R, shown
shaded in Figure 1, is bounded by the curve, the y-axis, the x-axis and the line with equation x =

3
.
(a) Copy and complete the table with values of y corresponding to x =
x
0

12
y
1.3229
1.2973


6
4

6
and x =

4
.

3
1
(2)
(b) Use the trapezium rule
(i) with the values of y at x = 0, x =

6
and x =

3
to find an estimate of the area of R.
Give your answer to 3 decimal places.
(ii) with the values of y at x = 0, x =




, x= ,x=
and x = to find a further estimate
12
6
4
3
of the area of R. Give your answer to 3 decimal places.
(6)
(C4, June 2010 Q1)
11.
C4 Integration
Page 13
Figure 2
Figure 2 shows a sketch of the curve with equation y = x3 ln (x2 + 2), x  0.
The finite region R, shown shaded in Figure 2, is bounded by the curve, the x-axis and the
line x = 2.
The table below shows corresponding values of x and y for y = x3 ln (x2 + 2).
x
0
y
0
2
4
2
2
3 2
4
2
0.3240
3.9210
(a) Complete the table above giving the missing values of y to 4 decimal places.
(2)
(b) Use the trapezium rule, with all the values of y in the completed table, to obtain an estimate
for the area of R, giving your answer to 2 decimal places.
(3)
(c) Use the substitution u = x2 + 2 to show that the area of R is
4
1
(u  2) ln u du .
2
2
(4)
(d) Hence, or otherwise, find the exact area of R.
(6)
(C4, June 2011 Q4)
12.
C4 Integration
Page 14
Figure 3 shows a sketch of the curve with equation y =

2 sin 2 x
, 0x .
2
(1  cos x)
The finite region R, shown shaded in Figure 3, is bounded by the curve and the x-axis.
The table below shows corresponding values of x and y for y =
x
0
y
0


8
2 sin 2 x
.
(1  cos x)

4
3
8
1.17157
1.02280
0
2
(a) Complete the table above giving the missing value of y to 5 decimal places.
(1)
(b) Use the trapezium rule, with all the values of y in the completed table, to obtain an estimate
for the area of R, giving your answer to 4 decimal places.
(3)
(c) Using the substitution u = 1 + cos x, or otherwise, show that
 2 sin 2 x
dx = 4 ln (1 + cos x) – 4 cos x + k,

 (1  cos x)
where k is a constant.
(5)
(d) Hence calculate the error of the estimate in part (b), giving your answer to 2 significant figures.
(C4, Jan2012 Q6)
13.
C4 Integration
Page 15
Figure 3
1
2
Figure 3 shows a sketch of part of the curve with equation y = x ln 2x.
The finite region R, shown shaded in Figure 3, is bounded by the curve, the x-axis and the lines
x = 1 and x = 4.
(a) Use the trapezium rule, with 3 strips of equal width, to find an estimate for the area of R,
giving your answer to 2 decimal places.
(4)

(b) Find  x 2 ln 2 x dx .

1
(4)
(c) Hence find the exact area of R, giving your answer in the form a ln 2 + b, where a and b are
exact constants.
(3)
(C4, June2012 Q7)
14.
C4 Integration
Page 16
Figure 1
x
. The finite region R, shown
1  x
shaded in Figure 1, is bounded by the curve, the x-axis, the line with equation x = 1 and the line
with equation x = 4.
Figure 1 shows a sketch of part of the curve with equation y =
(a) Copy and complete the table with the value of y corresponding to x = 3, giving your answer
to 4 decimal places.
(1)
x
1
2
y
0.5
0.8284
3
4
1.3333
(b) Use the trapezium rule, with all the values of y in the completed table, to obtain an estimate
of the area of the region R, giving your answer to 3 decimal places.
(3)
(c) Use the substitution u = 1 + x, to find, by integrating, the exact area of R.
(8)
(C4, Jan2013 Q4)
15.
C4 Integration
Page 17
Figure 1
Figure 1 shows the finite region R bounded by the x-axis, the y-axis, the line x =
curve with equation
1 
y = sec  x  ,
2 
0≤x≤

2
and the

2
1 
The table shows corresponding values of x and y for y = sec  x  .
2 
x
0
y
1



6
3
2
1.035276
1.414214
(a) Complete the table above giving the missing value of y to 6 decimal places.
(1)
(b) Using the trapezium rule, with all of the values of y from the completed table, find an
approximation for the area of R, giving your answer to 4 decimal places.
(3)
Region R is rotated through 2π radians about the x-axis.
(c) Use calculus to find the exact volume of the solid formed.
(4)
(C4, June2013Q3)
16.
C4 Integration
Page 18
Figure 1
1t
Figure 1 shows part of the curve with equation x  4te 3  3 . The finite region R shown shaded in
Figure 1 is bounded by the curve, the x-axis, the t-axis and the line t = 8.
(a) Complete the table with the value of x corresponding to t = 6, giving your answer to
3 decimal places.
t
0
2
4
x
3
7.107
7.218
6
8
5.223
(1)
(b) Use the trapezium rule with all the values of x in the completed table to obtain an estimate for
the area of the region R, giving your answer to 2 decimal places.
(3)
(c) Use calculus to find the exact value for the area of R.
(6)
(d) Find the difference between the values obtained in part (b) and part (c), giving your answer to
2 decimal places.
(1)
(C4, June2013_R, Q5)
17.
C4 Integration
Page 19
Figure 1
Figure 1 shows a sketch of part of the curve with equation y 
10
, x > 0.
2x  5  x
The finite region R, shown shaded in Figure 1, is bounded by the curve, the x-axis, and the lines
with equations x = 1 and x = 4.
The table below shows corresponding values of x and y for y 
x
1
2
y
1.42857
0.90326
10
.
2x  5  x
3
4
0.55556
(a) Complete the table above by giving the missing value of y to 5 decimal places.
(1)
(b) Use the trapezium rule, with all the values of y in the completed table, to find an estimate for
the area of R, giving your answer to 4 decimal places.
(3)
(c) By reference to the curve in Figure 1, state, giving a reason, whether your estimate in part (b)
is an overestimate or an underestimate for the area of R.
(1)
(d) Use the substitution u = √x, or otherwise, to find the exact value of

4
1
10
dx
2x  5  x
(6)
(C4, June2014, Q3)
C4 Integration
Page 20
18.
Figure 1
Figure 1 shows a sketch of part of the curve with equation
x
y = (2 – x)e2x,
The finite region R, shown shaded in Figure 1, is bounded by the curve, the x-axis and the
y-axis.
The table below shows corresponding values of x and y for y = (2 – x)e2x.
x
0
0.5
1
1.5
2
y
2
4.077
7.389
10.043
0
(a) Use the trapezium rule with all the values of y in the table, to obtain an approximation for the
area of R, giving your answer to 2 decimal places.
(3)
(b) Explain how the trapezium rule can be used to give a more accurate approximation for the
area of R.
(1)
(c) Use calculus, showing each step in your working, to obtain an exact value for the area
of R. Give your answer in its simplest form.
(5)
(C4, June2014_R, Q2)
C4 Integration
Page 21