Trigonometry Practice Questions for Junior Certificate Ordinary Level

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Practice solving trigonometry questions for the Junior Certificate Ordinary Level exam. Includes finding side lengths, calculating trigonometric ratios, and applying concepts such as Pythagoras' Theorem. Explore various scenarios involving right-angled triangles to enhance your understanding of trigonometry concepts.


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  1. Junior Certificate Ordinary Level Trigonometry www.mathsplus.ie www.mathsplus.ie www.mathsplus.ie

  2. Junior Certificate Ordinary Level Question 1 Question 1 www.mathsplus.ie www.mathsplus.ie www.mathsplus.ie

  3. (a) The right-angled triangle in the diagram has measurements as shown. Write down the length of the side opposite to angle A. (i) 12 12 Length of the side opposite to angle A = OPP HYP 12 (ii) Write down, as a fraction, the value of sin A. 15 ___ 15 =___ 5 4 A sin A = 9 opposite hypotenuse _________ sin =

  4. (b) XYZ, In the right-angled triangle |XZ| = 13, | YXZ| = 60 . Using your calculator, write down the value of cos 60 . Z (i) cos 60 = 0 5 HYP 13 (ii) Using the diagram, complete the following |XY| cos 60 = adjacent hypotenuse 60 13 Y X ADJ (iii) Hence calculate |XY|. |XY| = 13 0 5 = 6 5

  5. (c) As part of an activity lesson a group of students was asked to measure the height of the mast [RS]. The mast, [RS], is supported by the cable [RT]. R The students measured the distance from S to T and they also measured the angle STR. They found ST = 10 m and | STR| = 50 . OPP h 12 m 50 S T (i) Find the height of the mast RS. Give your answer correct to the nearest metre. 10 m ADJ opposite adjacent |RS| tan 50 = tan 50 = 10 |RS| = 1 1 917 2 m

  6. (c) As part of an activity lesson a group of students was asked to measure the height of the mast [RS]. The mast, [RS], is supported by the cable [RT]. R c The students measured the distance from S to T and they also measured the angle STR. They found ST = 10 m and | STR| = 50 . Pythagoras Theorem 12 m 50 S T 10 m a2 + b2= c2 (ii) Using the theorem of Pythagoras, or otherwise, find the length of the supporting cable, RT . Give your answer correct to the nearest metre. c2= 102 +122 c2= c = 15 62 100 + 144 244 6 m

  7. Junior Certificate Ordinary Level Question 2 Question 2 www.mathsplus.ie www.mathsplus.ie www.mathsplus.ie

  8. (a) measurements (i) triangle. The diagram shows a right-angled triangle with as shown. Write down the length of the hypotenuse of the HYP 41 X 9 ADJ 40 adjacent hypotenuse 9 _________ =__ cos X = 41 (ii) Write down the value of cos X as a fraction.

  9. C (b) In the right-angled triangle ABC, |AC| = 25 | BAC| = 32 . Let |BC| = x. 25 HYP x x = 25 0 53 = 13 25 OPP sin 32 = sin 32 = 0 5 299 3 opposite x = 32 hypotenuse 25 A B (i) Using your calculator find sin 32 . Write your answer correct to two decimal places. (ii) (iii) Using the diagram of the triangle ABC write sin 32 as a fraction. Hence, or otherwise, find x, the value of |CB| .

  10. (c) Se n wishes to measure the width of a canal. He is at a point A directly opposite a landmark B on the opposite bank. Se n walks 50 paces along the bank of the canal to point C. He measures the angle ACB and finds it is 25 . Each of Se n s paces is 0 7 m. Calculate |AC| . Hence calculate the width of the canal, |AB| . Give your answer to the nearest metre. 35 m ADJ (i) (ii) C A 25 50 0 7 = 35 m opposite x 35 x = 35 tan 25 = 16 3207.. m adjacent tan 25 = OPP x B

  11. Junior Certificate Ordinary Level Question 3 Question 3 www.mathsplus.ie www.mathsplus.ie www.mathsplus.ie

  12. (a) shown. (i) The right-angled triangle ABC has measurements as Write down the length of the side opposite the angle C. Length of the side opposite to the angle C = 24 OPP 24 B C ADJ 10 26 C (ii) Write down the value of tan C, as a fraction. opposite adjacent A 24 _______ =___ 10 tan =

  13. (b) In the right-angled triangle PQR, |PQ| = 14 and | PQR| = 53 . P Let |QR| = d. (i) (iii) Hence find d, the value of |QR|. Using the diagram write down the value of cos 53 , as a fraction. HYP 14 adjacent = 0 6 d hypotenuse 14 d = 14 0 6 = 8 4 cos 53 = cos 53 = 0 6018 . 53 Q R d ADJ (ii) Using your calculator, or otherwise, write down the value of cos 53 correct to one decimal place.

  14. (c) [ZW] is a vertical television aerial mast. [ZX] and [ZY] are supporting cables. |ZX| = 15 m, |XW| = 12 m and |WY| = 16 m. Z Theorem of Pythagoras Hypotenuse (Side 1)2+ (Side 2)2= (Hypotenuse)2 15 m 9 m |ZW|2+ 122 =152 |ZW| + 2144 = 225 81 A X Y 12 m 16 m W |ZW| = 9 m (i) In XWZ, use the Theorem of Pythagoras, to find |ZW| , the height of the television aerial mast.

  15. (c) [ZW] is a vertical television aerial mast. [ZX] and [ZY] are supporting cables. |ZX| = 15 m, |XW| = 12 m and |WY| = 16 m. A = tan 10 5625 = 29 3577 Z 15 m OPP 9 m A X Y 12 m 16 m ADJ W (ii) Hence find the measure of the angle marked A in the diagram correct to the nearest degree. opposite adjacent 9= 0 5625 =___ 16 _______ tan A =

  16. Junior Certificate Ordinary Level Question 4 Question 4 www.mathsplus.ie www.mathsplus.ie www.mathsplus.ie

  17. (a) shown. (i) The right-angled triangle ABC has measurements as Write down the length of the hypotenuse of the ABC. 17 C HYP 17 OPP 8 B A B 15 (ii) Write down the value of sin B, as a fraction. opposite hypotenuse 8 _________ =___ 17 sin =

  18. P (b) In the right-angled triangle PQR, |QR| = 4, | QPR| = 48 and | PQR| = t . 48 (i) Find the value of t. t = 90 48 = 42 (ii) Using your calculator, or otherwise, write down the value of tan | PQR| correct to one decimal place. OPP tan | PQR| = tan 42 t 42 = 0 9004.. Q R 4 ADJ (iii) Hence, or otherwise, calculate |PR| correct to one decimal place. opposite tan 42 = 4 |PR| = 3 6 |PR| 0 9 = Multiply by 4 adjacent

  19. (c) In the ABC, | BCA| = 90 , |AB| = 25 m and |BC| = 24 m. (i) Find, in metres, |AC|. B Pythagoras Theorem Pythagoras Theorem (Side 1)2+ (Side 2)2= (Hypotenuse)2 242+ |AC|2= 252 |AC|2= 625 576 + |AC|2= 25 m 24 m = 49 = 7 m = 7 m A C 7 m

  20. (c) In the ABC, | BCA| = 90 , |AB| = 25 m and |BC| = 24 m. (ii) Find | BAC|, correct to the nearest degree. B opposite hypotenuse __________ sin | BAC| = 24 25 =___ HYP 25 m OPP | BAC| = 73 739 24 m = 74 A C 7 m

  21. Junior Certificate Ordinary Level Question 5 Question 5

  22. (a) shown. (i) The right-angled triangle ABC has measurements as Write down the length of the hypotenuse of the ABC. 10 Write down the value of cos C C HYP 10 6 (ii) C, ADJ as a fraction. cos =__________ A B 8 adjacent hypotenuse 6 =__ 5 =__ 10 3

  23. P (b) PQR, In the right-angled triangle |PQ| = 8 and | PQR| = 50 . 40 (i) Find | QPR|. 8 | QPR| = 180 90 50 . = 40 50 R Q (ii) Using your calculator, or otherwise, write down the value of sin | QPR| correct to two decimal places. sin 40 = 0 64278 ..

  24. P (b) PQR, In the right-angled triangle |PQ| = 8 and | PQR| = 50 . 40 (iii) Hence, or otherwise, calculate |QR| correct to one decimal place. HYP 8 5 opposite |QR| sin 40 = hypotenuse 8 From part (ii) Multiply both sides by 8 |QR| = 8 0 64 |QR| = 5 12 |QR| = 5 1 50 R Q OPP

  25. (c) 5 m. In the ABC, | BCA| = 90 , |AB| =13 m and |AC| = B (i) Find, in metres, |BC|. Pythagoras Theorem (Side 1)2+ (Side 2)2= (Hypotenuse)2 52+ |BC|2= 132 |BC|2= 169 25 + |BC|2= 13 m 144 = 12 m A C 5 m

  26. (c) = 5 m. In the ABC, | BCA| = 90 , |AB| =13 m and |AC| B (ii) Find | BAC|, correct to the nearest degree. adjacent hypotenuse sin =__________ HYP OPP 13 m 12 m 12 __ sin | BAC| = 13 | BAC| = 67 38.. A C 5 m ADJ

  27. Junior Certificate Ordinary Level Question 6 Question 6 www.mathsplus.ie www.mathsplus.ie www.mathsplus.ie

  28. (a) shown. (i) The right-angled triangle ABC has measurements as Write down the length of the side opposite the angle A. 24 24 A B OPP (ii) A, Write down the value of tan ADJ 7 25 as a fraction. opposite tan =_______ A C adjacent 24 7 =___

  29. (b) PQR, In the right-angled triangle |PQ| = 12 and | QPR| = 60 . P (i) value Write down the 60 of cos 60 . 12 HYP ADJ cos 60 = 0 5 (ii) PR|. Calculate | R Q adjacent |PR| 0 5 = cos 60 = Cross multiply hypotenuse 12 |PR| = 6

  30. (c) Claire is at a point c on the top of a cliff. The point B is at the base of the cliff. The height of the cliff is 35 m, as shown in the diagram. She wishes to find |BA|, the distance from the base of the cliff to the base of the lighthouse. She measured DCA and found it to be 41 . CD is parallel to BA. (i) Find | BAC|. C D 41 Alternate angles 35 m | BAC| = 41 41 A B

  31. (c) Claire is at a point c on the top of a cliff. The point B is at the base of the cliff. The height of the cliff is 35 m, as shown in the diagram. She wishes to find |BA|, the distance from the base of the cliff to the base of the lighthouse. She measured DCA and found it to be 41 . CD is parallel to BA. (ii) Find, to the nearest metre, |BA|, the distance from the base of the cliff to the base of the lighthouse. C D opposite adjacent 35 41 tan 41 = tan 41 = 35 m OPP |BA| = 40 262 = 40 metres 41 A B 40 m ADJ

  32. Junior Certificate Ordinary Level Question 7 Question 7

  33. (a) shown. (i) The right-angled triangle ABC has measurements as Write down the length of the side adjacent to angle A. C 15 Length of the side adjacent to angle A = HYP 17 8 A A B 15 ADJ (ii) Write down the value of cos A, as a fraction. adjacent hypotenuse 15 =___ 17 _________ cos =

  34. P (b) In the right-angled triangle PQR, |PQ| = 12, | PQR| = 37 . Let x = |PR|. Using the diagram, write down the value of sin 37 as a fraction. opposite sin 37 = 0 6 = (i) HYP x 12 hypotenuse 12 OPP x (ii) Using your calculator,write down the value of sin 37 correct to one decimal place. 37 sin 37 = 0 6018 . Q R (iii) Hence find x, the value of |PR|. x = 7 2

  35. (c) Ciara wished to measure the width of a river. She was at A on the riverbank, directly opposite B on the other bank. Ciara walked from A to C, along the riverbank, at an average speed of 1 5 m/s. It took Ciara 30 seconds to reach C. She then measured ACB and found it to be 25 . B D S T 25 C A 45 m (i) by Ciara. Calculate |AC| , the distance walked Distance = Speed Time = 1 5 30 = 45 metres

  36. (c) Ciara wished to measure the width of a river. She was at A on the riverbank, directly opposite B on the other bank. Ciara walked from A to C, along the riverbank, at an average speed of 1 5 m/s. It took Ciara 30 seconds to reach C. She then measured ACB and found it to be 25 . B OPP 25 C A 45 m ADJ (ii) the river. Hence, calculate |AB| , the width of Give your answer correct to the tan 25 = adjacent opposite |AB| tan 25 = nearest metre. 45 1 m |AB| = 20 983

  37. Junior Certificate Ordinary Level Question 8 Question 8

  38. (a) shown. (i) The right-angled triangle ABC has measurements as Write down the length of the side opposite the angle A. 5 C HYP 13 OPP 5 A B A 12 (ii) Write down the value of sin A, as a fraction. opposite hypotenuse 5 _________ =___ 13 sin =

  39. (b) PQR, In the right-angled triangle P |PQ| = 10 and |PR| = 4. Find the value of cos PQR . (i) HYP 10 adjacent 4 = 0 4 hypotenuse 10 cos PQR = (ii) Hence find the measure of PQR, correct to the nearest degree. PQR = cos 10 4 Q R 4 = 66 421... ADJ = 66

  40. (c) angle of 20 An aeroplane leaves the ground at an to the runway. Its speed is 28 m/sec. How far does the aeroplane travel in the first 30 seconds? (i) 840 m 20 Take-off point Distance = Speed Time = 28 30 D S T = 840 metres

  41. (c) angle of 20 (ii) after the An aeroplane leaves the ground at an to the runway. Its speed is 28 m/sec. What is its height above the ground first 30 seconds? Write your answer to the nearest metre. HYP 840 m OPP h 20 Take-off point opposite h sin 20 = hypotenuse 840 h = 287 296.. metres

  42. Junior Certificate Ordinary Level Question 9 Question 9

  43. (a) shown. (i) The triangle abc has measurements as Write down the value of cos A. b adjacent hypotenuse 4 =__ _________ cos A = HYP 5 5 OPP 3 (ii) Write down the value of tan A. A a c 4 3 opposite adjacent =__ _______ ADJ tan A = 4

  44. (b) A vertical building is 8 m high. It casts a shadow three times its height on horizontal ground. (i) Write down the length of the shadow. 3 8 = 24 m OPP 8 m B 24 m ADJ (ii) Find B, the angle of elevation of the sun, correct to the nearest degree. opposite tan B =8 adjacent 24 8 = 18 4349 24 B = tan 1

  45. (c) A vertical flagpole [PQ], 12 m high, is supported by a cable [QR] as shown in the diagram. Q opposite hypotenuse _________ HYP 24 m sin A = OPP x 12 m 30 R P (i) Given that | QRP| = 30 , find the length of the cable [QR]. opposite 12 = 24 m sin 30 0 5 = hypotenuse x

  46. (c) A vertical flagpole [PQ], 12 m high, is supported by a cable [QR] as shown in the diagram. Q Pythagoras Theorem HYP OPP 24 m a2 + b2= c2 12 m 30 R P y (ii) How far is R from P, the foot of the flagpole? Give your answer correct to one decimal place. y2+ 122 =242 y2+ 144 = 576 y2= 576 144 432 y = 20 784 8 m

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