Robinson Tuition
Grade 7 · Higher · free GCSE maths worksheet

Sine rule

Non-right-angled triangles.

15 original questions, 62 marks. Print the worksheet, mark it with the answers sheet, and use the solutions to see every step written out by hand.

Worksheet PDFWorked solutions PDFAnswers PDF

The questions

1

In triangle ABC, angle BAC = 35°, angle ABC = 78° and BC = 9.4 cm.

Work out the length of AC. Give your answer correct to 3 significant figures.

9.4 cm35°78°ABCDiagram NOT accurately drawn
3 marks
Show answer
16.0 cm
2

In triangle ABC, angle BAC = 52°, angle ACB = 63° and AC = 11 cm.

Calculate the length of BC. Give your answer correct to 3 significant figures.

11 cm52°63°ABCDiagram NOT accurately drawn
3 marks
Show answer
9.56 cm
3

In triangle ABC, AB = 12.5 cm, BC = 8.4 cm and angle BAC = 33°.

Angle ACB is acute.

Work out the size of angle ACB. Give your answer correct to 1 decimal place.

12.5 cm8.4 cm33°ABCDiagram NOT accurately drawn
4 marks
Show answer
54.1°
4

In triangle PQR, QR = 14.2 cm, PR = 9.6 cm and angle QPR = 81°.

Calculate the size of angle PQR. Give your answer correct to 1 decimal place.

14.2 cm9.6 cm81°PQRDiagram NOT accurately drawn
4 marks
Show answer
41.9°
5

B is due east of A. AB = 250 m.

The bearing of a mast C from A is 040°.

The bearing of C from B is 300°.

Work out the distance AC. Give your answer correct to 3 significant figures.

250 m040°300°ABCNNDiagram NOT accurately drawn
4 marks
Show answer
127 m
6

In triangle ABC, angle ABC = 45°, angle ACB = 60° and AB = 6√2 cm.
Without using a calculator, show that AC = 4√3 cm.

6√2 cm45°60°ABCDiagram NOT accurately drawn
4 marks
Show answer
AC = 4√3 cm
7

In triangle ABC, angle BAC = 30°, BC = 5 cm and AB = 8 cm.

Work out the exact value of sin C.

8 cm5 cm30°ABCDiagram NOT accurately drawn
4 marks
Show answer
45
8

In triangle ABC, AB = 10 cm, BC = 7 cm and angle BAC = 40°.
Angle ACB could be acute or obtuse. Work out both possible sizes of angle ACB. Give each answer correct to 1 decimal place.

10 cm7 cm40°ABCDiagram NOT accurately drawn
4 marks
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acute) 66.7° obtuse) 113.3°
9

A triangular sail has angles of 71° and 44°.

The side opposite the 71° angle has length 6.4 m.

Work out the length of the side opposite the 44° angle. Give your answer correct to 3 significant figures.

6.4 m71°44°ABCDiagram NOT accurately drawn
4 marks
Show answer
4.70 m
10

A boat leaves harbour H and sails 8 km on a bearing of 070° to a buoy B. A lighthouse L is due north of H. From B, the bearing of L is 320°.
Sketch the triangle HBL, then work out the distance HL. Give your answer correct to 3 significant figures.

5 marks
Show answer
11.7 km
11

In triangle ABC, angle BAC = 25°, BC = 7.2 cm and AB = 13.5 cm.

Angle ACB is obtuse.

Work out the size of angle ACB. Give your answer correct to 1 decimal place.

13.5 cm7.2 cm25°ABCDiagram NOT accurately drawn
4 marks
Show answer
127.6°
12

The diagram shows quadrilateral ABCD. The diagonal BD splits it into triangles ABD and BCD.

In triangle ABD, angle DAB = 58°, angle ABD = 47° and AD = 9.3 cm.

In triangle BCD, angle DBC = 39° and angle BCD = 64°.

Work out the length of CD. Give your answer correct to 3 significant figures.

9.3 cm58°39°64°47°ABCDDiagram NOT accurately drawn
5 marks
Show answer
7.55 cm
13

In triangle ABC, angle BAC = 50°, angle ABC = 70° and AC = 12 cm.
Work out the area of triangle ABC. Give your answer correct to 3 significant figures.

12 cm50°70°ABCDiagram NOT accurately drawn
5 marks
Show answer
50.8 cm2
14

In triangle ABC, AB = 12 cm, angle BAC = 40° and angle ABC = 75°.

Work out the perimeter of the triangle. Give your answer correct to 3 significant figures.

12 cm40°75°ABCDiagram NOT accurately drawn
5 marks
Show answer
33.3 cm
15

In triangle ABC, the point D lies on the side BC. The line AD bisects angle BAC.
Use the sine rule in triangles ABD and ACD to prove that BDDC = ABAC

4 marks
Show answer
BD/DC = AB/AC

Every question here is original and written by Robinson Tuition. The grade follows the Edexcel grade descriptors and suits AQA and OCR too; this is not an exam-board paper.

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