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The sine rule and the cosine rule worksheet — GCSE Higher

Fifteen questions on "the sine rule and the cosine rule" — DfE statement G22. Print it, or print three versions so neighbours cannot copy by letter; the key gives the letter for each version.

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The sine rule and the cosine rule worksheet — GCSE Higher

Maths · GCSE Higher · G22 · The sine rule and the cosine rule · 15 questions

MathsUKwww.geekhero.co.uk

1.Two coastguard stations A and B are 18 km apart, with B due east of A. A boat at C is on a bearing of 062° from A and on a bearing of 315° from B. Work out the distance of the boat from station B. Give your answer to 1 decimal place.
(a)16.6 km
(b)13.3 km
(c)12.0 km
(d)8.8 km
2.In triangle PQR, PQ = 11 cm, QR = 7 cm and PR = 13 cm. Work out the size of angle PQR. Give your answer to 1 decimal place.
(a)89.6°
(b)32.6°
(c)90.4°
(d)89.8°
3.Which of these statements about solving a triangle is correct?
(a)Two sides + a non-included angle: cosine rule gives the angle directly.
(b)Two sides + angle between them: use the sine rule.
(c)All three sides: use the sine rule for any angle.
(d)Two angles and a side: sine rule finds other sides.
4.A triangle has one unknown side or angle, marked x. In which one of these situations should the sine rule, rather than the cosine rule, be used to find x?
(a)Two sides and the included angle; x is the third side
(b)Two sides and the included angle; x is another angle
(c)Two angles and one side are known; x is another side
(d)All three sides are known; x is one of the angles
5.In triangle ABC, AB = 5 cm, BC = 3 cm and AC = 7 cm. Work out the size of angle ABC.
(a)120°
(b)150°
(c)90°
(d)60°
6.In triangle ABC, AB = 6 cm, angle ABC = 40° and AC = 9 cm. Using the sine rule, sin(ACB) = AB × sin(ABC) ÷ AC, which gives two possible values for angle ACB: 25.4° or 154.6° (each to 1 decimal place). By considering the angle sum of the triangle, decide which of these two values angle ACB can actually take, and hence work out angle BAC. Give your answer to 1 decimal place.
(a)114.6°
(b)14.6°
(c)65.4°
(d)25.4°
7.In triangle ABC, AB = 8 cm, AC = 5 cm and angle BAC = 60°. Work out the value of BC².
(a)49 cm²
(b)129 cm²
(c)69 cm²
(d)89 cm²
8.A student is asked to rearrange the cosine rule a² = b² + c² − 2bc cos A to make cos A the subject. They write: cos A = (a² − b² − c²) / (2bc). Is the student's rearrangement correct?
(a)Yes — the sign does not matter for cos A.
(b)No — should divide by −2bc, not +2bc; sign is wrong.
(c)No — the denominator should be bc, not 2bc.
(d)Yes — the rearrangement is correct as written.
9.In triangle ABC, angle ABC = 72° and angle ACB = 48°. Side AB = (2x + 1) cm and side AC = (3x − 2) cm. Work out the value of x. Give your answer to 1 decimal place.
(a)4.7
(b)7.4
(c)1.9
(d)3.0
10.In triangle ABC, AB = 9 cm, AC = 6 cm and angle BAC = 110°. Work out the length of BC. Give your answer to 1 decimal place.
(a)11.6 cm
(b)153.9 cm
(c)12.4 cm
(d)8.9 cm
11.A tent frame forms a triangle ABC, where AB = 3.5 m is a sloping pole, BC = 2.8 m is the base and AC = 4.2 m is the guy rope. Work out the size of angle ABC, between the pole and the base. Give your answer to 1 decimal place.
(a)75.5°
(b)97.2°
(c)41.4°
(d)82.8°
12.In triangle ABC, AB = 12 cm, AC = 9 cm and angle BAC = 55°. Work out the size of angle ABC. Give your answer to 1 decimal place.
(a)77.8°
(b)47.2°
(c)37.9°
(d)23.2°
13.In triangle ABC, AB = x cm, AC = (x + 2) cm, BC = 15 cm and angle BAC = 100°. Work out the value of x. Give your answer to 1 decimal place.
(a)10.8
(b)9.6
(c)10.6
(d)8.8
14.A ship leaves port P and sails 24 km on a bearing of 040° to a buoy Q. It then sails 31 km on a bearing of 115° to a lighthouse R. Work out the direct distance from P to R. Give your answer to 1 decimal place.
(a)33.9 km
(b)43.8 km
(c)55.0 km
(d)19.9 km
15.In triangle ABC, AB = x cm, AC = (x + 3) cm, BC = 7 cm and angle BAC = 60°. Work out the value of x.
(a)5
(b)37
(c)−8
(d)8

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