Trigonometric Formulae & Identities (Edexcel IGCSE Further Pure Maths): Exam Questions

Exam code: 4PM1

2 hours16 questions
1
3 marks
Triangle AOB and sector BOC. OA is 10 cm, OB and OC are 6 cm each, and arc BC is π cm. Centred at O, labelled as Figure 1.

Figure 1 shows a shape A B C spacein which A O B is a triangle, A O C is a straight line and O B C is a sector of a circle with centre O.

A O space equals space 10 spacecm comma space O C space equals space O B space equals space 6 spacecm and the length of arc B C space equals space pi cm.

Find, to 3 significant figures, the length of A B.

2
4 marks
Diagram of a pyramid with triangular base ABC and apex O. Sides OA and OC are 12 cm, AB and AC are 8 cm, and height OD is labelled. Diagram not to scale.

Figure 2 shows a right pyramid A B C D O spacewith a horizontal square base of side 8 cm. The vertical height of the pyramid is h cm and O A space equals space O B space equals space O C space equals space O D space equals space 12 cm.

The midpoint of OA is P and Q is the point on BC such that BQ : QC = 3 :1

Find, to 1 decimal place, the size of angle P Q A.

3a
2 marks

Show that cos left parenthesis A space – space B right parenthesis space – space cos left parenthesis A space plus space B right parenthesis space equals space 2 sin space A space sin space B

3b
1 mark

Hence express space 2 sin space 5 x space sin space 3 x in the form cos space m x space – space cos space n x spacewhere m and n are integers, giving the value of m and the value of n,

4
4 marks

In triangle A B C, A B space= 2 xcm, B C space equals space 3 x cm and A C space equals space 4 x cm

The area of triangle A B C is 50 cm2

Find, to 2 decimal places, the value of x

5a
3 marks
Irregular hexagon with vertices A, B, C, D, E, F, and internal angles 60° and 45°. Diagram indicates "not accurately drawn." Side AB is 24 cm.

Figure 5 shows a right triangular prism A B C D E F spacewhere A B C D is a rectangle.

A F space equals space D E     B F space equals space C E     A D space equals space F E space equals space B C     A B space equals space D C space equals space 24 cm

angle A B F space equals space angle D C E space equals space 45 degree     angle B A F space equals space angle C D E space equals 60 degree

Using a formula from page 2 (opens in a new tab),

show that space sin space A F B space equals space fraction numerator square root of 2 plus square root of 6 over denominator 4 end fraction

5b
5 marks

Without using a calculator,

show that B F space equals space 12 open parentheses 3 square root of 2 space minus space square root of 6 close parenthesescm

6a
3 marks

Using formulae (opens in a new tab), show that cos space 2 A space equals space 2 space cos to the power of 2 space space end exponent A space minus space 1

6b
1 mark

Using formulae from page 2 (opens in a new tab), show that sin space 2 space A space equals space 2 sin space A space cos space A

6c
4 marks

Show that cos cubed space A space equals space fraction numerator cos space 3 A space plus space 3 space cos space A space over denominator 4 end fraction

6d
4 marks

Hence, or otherwise, solve, giving exact values in terms of pi

8 space cos cubed space open parentheses theta over 2 close parentheses space minus space 6 space cos space open parentheses theta over 2 close parentheses space minus space 1 space equals space 0 for 0 space less-than or slanted equal to space theta space less-than or slanted equal to space 2 straight pi

7
5 marks

Triangle A B C spaceis such that

A C space equals 10 space cm space space space space space space space space space B C space equals space 7 space cm     angle space C A B space equals space 25 degree

Given that angle A B C spaceis obtuse,

find, in cm to one decimal place, the length of space A B

8a
2 marks

Using a formula (opens in a new tab), show that

tan space 2 A equals fraction numerator 2 space tan space A over denominator 1 minus tan squared space A end fraction

8b
5 marks

Hence, solve the equation

tan space A degree minus tan space 2 A degree equals 0 for 0 less-than or slanted equal to A less-than or slanted equal to 180

8c
4 marks

Using a formula given on page 2, solve, giving your solutions as exact values

cos open parentheses x minus pi over 6 close parentheses equals sin x for negative pi less-than or slanted equal to x less-than or slanted equal to 2 pi

9
4 marks
Triangle OAB with intersecting line OCD. Points A, B, C, D, and O labelled. Note states diagram is not accurately drawn.

Figure 2 shows triangle A O B

stack O A with rightwards arrow on top equals 4 bold a plus 5 bold b    stack O B with rightwards arrow on top equals 8 bold a minus bold b bold space space stack O D with rightwards arrow on top equals 15 bold a plus 10 bold b where vertical line bold a vertical line equals vertical line bold b vertical line equals 1

Find the area of triangle A O B

10
2 marks

Using a formula (opens in a new tab), show that

cos space 2 theta equals 2 space cos squared space theta minus 1

11a
4 marks

Using the formulae (opens in a new tab) , show that

(i) cos squared space A equals fraction numerator cos space 2 space A plus 1 over denominator 2 end fraction

(ii) sin squared space A equals fraction numerator 1 minus cos space 2 space A over denominator 2 end fraction

11b
5 marks

Show that

left parenthesis 2 space sin space x minus cos space x right parenthesis left parenthesis sin space x minus 3 space cos space x right parenthesis equals 1 half left parenthesis cos space 2 x minus 7 space sin space 2 x plus 5 right parenthesis

11c
4 marks

y equals left parenthesis 2 space sin x minus cos space x right parenthesis left parenthesis sin space x minus 3 space cos space x right parenthesis

Solve, for 0 degree less-than or slanted equal to x less-than or slanted equal to 180 degree the equation, fraction numerator straight d y over denominator straight d x end fraction equals 0

Give your answers to the nearest whole number.

12
1 mark
Diagram showing two adjacent triangles, each with sides of 5 cm and r cm, and angles π/3 radians. The figure is labelled with points A to F.

Figure 3 shows a right triangular prism A B C D E F. A cross section A B C of the prism is a triangle in which A B equals A C equals r space cm and angle C A B equals pi over italic 3radians.

In the prism

A E equals B F equals C D equals 5 text  cm end text      E D equals E F equals r text  cm end text and angle D E F equals pi over italic 3 radians.

Show that the volume of the prism is fraction numerator 5 square root of 3 over denominator 4 end fraction   r squared space text cm end text cubed

13a
3 marks

Using formulae (opens in a new tab) , show that

(i) sin space 2 A equals 2 space sin space A space cos space A

(ii) cos space 2 A equals 2 cos squared space A minus 1

13b
4 marks

f open parentheses theta close parentheses equals fraction numerator 2 tan theta over denominator 1 plus tan squared theta end fraction

Show that straight f left parenthesis theta right parenthesis equals sin space 2 theta

13c
6 marks

Solve, in radians to 3 significant figures, for negative pi over 2 less-than or slanted equal to x less-than or slanted equal to pi over 2, the equation

5 space tan open parentheses x plus pi over 6 close parentheses equals open square brackets 1 plus tan squared open parentheses x plus pi over 6 close parentheses close square brackets open square brackets 1 minus 2 space cos squared open parentheses x plus pi over 6 close parentheses close square brackets

14a
4 marks

In triangle A B C, A B equals 3 x space cm, B C equals 5 x space cm and angle A B C equals 110 degree

Find, in degrees to one decimal place, the size of angle B C A

14b
3 marks

In triangle A B C, A B equals 3 x space cm, B C equals 5 x space cm and angle A B C equals 110 degree

The area of triangle A B C is 24 cm2

Find, to 3 significant figures, the value of x

15
4 marks
Triangle XYZ with sides labelled: XY as (x+2) cm, XZ as (2x+4) cm, and YZ as (2x-1) cm. Angle X is 60 degrees. Diagram not to scale.

Figure 1 shows triangle X Y Z in which

X Y equals left parenthesis x plus 2 right parenthesis text  cm end text      X Z equals left parenthesis 2 x plus 4 right parenthesis text  cm end text      Y Z equals left parenthesis 2 x minus 1 right parenthesis text  cm end text      and space space angle Y X Z equals 60 degree

Find the value of x

Give your answer in the form p plus q square root of 3 where p and q are integers to be found.

16a
5 marks

Using the formulae (opens in a new tab), show that

(i) sin space 2 theta equals 2 space sin space theta space cos space theta

[2]

(ii) cos space 2 theta equals 2 cos squared space theta minus 1

[3]

16b
4 marks

Given that theta not equal to left parenthesis 90 degree plus 180 degree n right parenthesis where n element of straight integer numbers

use the results from part (a) to show that sin space 2 theta minus tan space theta can be written as tan space theta space cos space 2 theta

16c
4 marks

Solve for 0 less than x less than 360

sin space 2 x degree minus tan space x degree equals 0