2023 Oct/Nov · Paper 12 · Q55 marksTrigonometric equations
2023 Oct/Nov · Paper 22 · Q10 (a, b)10 marksIdentities and proofs · Trigonometric equations
2023 May/June · Paper 12 · Q13 marksTrigonometric graphs
2023 May/June · Paper 12 · Q6 (a, b)7 marksIdentities and proofs · Trigonometric equations
2022
2022 Oct/Nov · Paper 12 · Q13 marksTrigonometric graphs
2022 Oct/Nov · Paper 12 · Q45 marksTrigonometric equations
2022 Oct/Nov · Paper 22 · Q7 (a, b)8 marksIdentities and proofs · Trigonometric equations
2022 Oct/Nov · Paper 22 · Q9 (a, b, c)11 marksSine and cosine rules (exact values)
2022 May/June · Paper 12 · Q13 marksTrigonometric graphs
2022 May/June · Paper 12 · Q24 marksIdentities and proofs
2022 May/June · Paper 22 · Q8 (b)5 marksTrigonometric equations
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Practice questions
Original questions written by HomiLabs in the style of the exam, with answers and mark schemes. They are not
Cambridge past paper questions and have not been reviewed by Cambridge. Try each one before opening the answer.
Q1Trigonometric equations · Core · Paper 1 style · no calculator · 3 marks
(a)Solve the equation 2 cos(x − 30°) = 1 for 0° ≤ x ≤ 360°.[3]
Show answer
(a) x = 90°, 330°
cos(x − 30°) = ½ M1; x − 30° = 60°, 300° (range −30° to 330°) M1; x = 90°, 330° A1
Q2Trigonometric equations · Core · Paper 2 style · calculator · 3 marks
(a)Solve tan 2x = 3 for 0° ≤ x ≤ 180°. Give your answers correct to 1 decimal place.[3]
Q5Trigonometric equations · Standard · Paper 1 style · no calculator · 5 marks
(a)Do not use a calculator in this question.Solve the equation 2 cos²x + 3 sin x = 3 for 0 ≤ x ≤ 2π radians, giving your answers as exact multiples of π.[5]
Show answer
(a) x = π/6, π/2, 5π/6
Use cos²x = 1 − sin²x M1; 2sin²x − 3sin x + 1 = 0 A1; (2sin x − 1)(sin x − 1) = 0 M1; sin x = ½ → π/6, 5π/6 A1; sin x = 1 → π/2 A1
Q6Trigonometric equations · Standard · Paper 2 style · calculator · 5 marks
(a)Solve cot(2y + π/4) = 0.5 for −π ≤ y ≤ π radians. Give your answers correct to 3 significant figures.[5]
Show answer
(a) y = −2.98, −1.41, 0.161, 1.73
tan(2y + π/4) = 2 M1; 2y + π/4 = 1.1071 + nπ M1; range for 2y + π/4 is −7π/4 to 9π/4 M1; y = ((1.1071 + nπ) − π/4)/2 for n = −2, −1, 0, 1 A2 (A1 for any two correct)
Q7Trigonometric equations · Standard · Paper 2 style · calculator · 6 marks
(a)Solve 4 cosec²x + cot x − 7 = 0 for 0° < x < 360°. Give your answers correct to 1 decimal place where necessary.[6]
Show answer
(a) x = 53.1°, 135°, 233.1°, 315°
cosec²x = 1 + cot²x M1; 4cot²x + cot x − 3 = 0 A1; (4cot x − 3)(cot x + 1) = 0 M1; cot x = ¾ → tan x = 4/3 → 53.1°, 233.1° A1 A1; cot x = −1 → 135°, 315° A1
Q8Trigonometric equations · Standard · Paper 2 style · calculator · 4 marks
(a)Solve tan x + 3 cot x = 4 for 0° < x < 180°.[4]
Show answer
(a) x = 45°, 71.6°
Multiply by tan x: tan²x − 4tan x + 3 = 0 M1 A1; (tan x − 1)(tan x − 3) = 0 → x = 45° A1, x = 71.6° A1
Q9Trigonometric equations · Standard · Paper 2 style · calculator · 4 marks
(a)Solve 3 sin x cos x = 2 cos x for 0° ≤ x ≤ 360°. Give your answers correct to 1 decimal place where necessary.[4]
Show answer
(a) x = 41.8°, 90°, 138.2°, 270°
cos x(3 sin x − 2) = 0 M1 (do not divide by cos x); cos x = 0 → 90°, 270° A1; sin x = ⅔ → 41.8° A1, 138.2° A1
Q10Trigonometric equations · Standard · Paper 2 style · calculator · 4 marks
(a)Solve cosec(x + 1) = −3 for 0 ≤ x ≤ 2π, where x is in radians. Give your answers correct to 3 significant figures.[4]
Show answer
(a) x = 2.48, 4.94
sin(x + 1) = −⅓ M1; x + 1 lies between 1 and 2π + 1; x + 1 = π + 0.3398 = 3.4814 or 2π − 0.3398 = 5.9434 M1 A1; x = 2.48, 4.94 A1
Q11Trigonometric equations · Challenge · Paper 2 style · calculator · 5 marks
(a)Solve sec(3x − 20°) = −2.5 for 0° ≤ x ≤ 180°. Give your answers correct to 1 decimal place.[5]
Show answer
(a) x = 44.5°, 88.8°, 164.5°
cos(3x − 20°) = −0.4 M1; 3x − 20° = 113.58°, 246.42°, 473.58° (range −20° to 520°) M1 A1; x = values ÷ 3 after adding 20° M1; all three correct, no extras A1
Q12Trigonometric equations · Challenge · Paper 2 style · calculator · 6 marks
(a)Show that sin²A/(1 − cos A) ≡ 1 + cos A.[2]
(b)Hence solve 5 sin²(2x) = 3(1 − cos 2x) for 0° < x < 180°. Give your answers correct to 1 decimal place.[4]
Show answer
(a) Shown
sin²A = 1 − cos²A = (1 − cos A)(1 + cos A) M1; cancel (1 − cos A) A1
(b) x = 56.8°, 123.2°
sin²2x/(1 − cos 2x) = 3/5 so 1 + cos 2x = 0.6 M1; cos 2x = −0.4 A1; 2x = 113.58°, 246.42° M1; x = 56.8°, 123.2° A1 (cos 2x = 1 gives x = 0° or 180°, outside the range)
Q13Trigonometric equations · Challenge · Paper 1 style · no calculator · 6 marks
(a)Do not use a calculator in this question.Factorise 2s³ − s² − 2s + 1 completely.[2]
(b)Hence solve 2 sin³x − sin²x − 2 sin x + 1 = 0 for 0° ≤ x ≤ 360°.[4]
sin x = ½ → 30°, 150° B1 B1; sin x = 1 → 90° B1; sin x = −1 → 270° B1
Q14Trigonometric equations · Challenge · Paper 2 style · calculator · 6 marks
(a)Solve 3 cos²y − 2 = sin y for 0 ≤ y ≤ 2π radians. Give your answers correct to 3 significant figures.[6]
Show answer
(a) y = 0.449, 2.69, 4.02, 5.41
3(1 − sin²y) − 2 − sin y = 0 M1; 3sin²y + sin y − 1 = 0 A1; sin y = (−1 ± √13)/6 = 0.4343 or −0.7676 M1; y = 0.449, 2.69 A1; y = 4.02, 5.41 A1 A1
Q15Trigonometric graphs · Core · Paper 1 style · no calculator · 4 marks
(a)For the curve y = 3 sin 2x + 1, state the amplitude.[1]
(b)State the period of y = 3 sin 2x + 1 in degrees.[1]
(c)State the greatest and least values of y.[2]
Show answer
(a) 3
B1
(b) 180°
360° ÷ 2 B1
(c) greatest 4, least −2
3 + 1 = 4 B1; −3 + 1 = −2 B1
Q16Trigonometric graphs · Core · Paper 1 style · no calculator · 4 marks
(a)State the amplitude and the period, in degrees, of y = 6 cos(x/3).[2]
(b)State the period of y = tan 4x in degrees.[1]
(c)The curve y = 2 sin x + k has least value −5. Find k.[1]
Show answer
(a) amplitude 6, period 1080°
B1 B1
(b) 45°
180° ÷ 4 B1
(c) k = −3
−2 + k = −5 B1
Q17Trigonometric graphs · Standard · Paper 1 style · no calculator · 7 marks
(a)The curve y = 2 cos 3x − 1 is drawn for 0° ≤ x ≤ 180°. State the period of the curve.[1]
(b)State the coordinates of the maximum and minimum points of the curve in this interval.[3]
(c)Find the x-coordinates of the points where the curve crosses the x-axis.[3]
Show answer
(a) 120°
360° ÷ 3 B1
(b) maxima (0°, 1) and (120°, 1); minima (60°, −3) and (180°, −3)
B1 maxima, B1 minima values, B1 all four x-coordinates
(c) x = 20°, 100°, 140°
cos 3x = ½ M1; 3x = 60°, 300°, 420° M1; x = 20°, 100°, 140° A1
Q18Trigonometric graphs · Standard · Paper 1 style · no calculator · 3 marks
(a)The curve y = a sin bx + c, where a, b and c are positive constants, has a maximum point at (30°, 7). The next minimum point to the right is at (90°, −1). Find a, b and c.[3]
Show answer
(a) a = 4, b = 3, c = 3
a = (7 − (−1))/2 = 4 B1; c = (7 + (−1))/2 = 3 B1; half period 60° so period 120°, b = 3 B1 (check: 3 × 30° = 90° gives sin = 1)
Q19Trigonometric graphs · Standard · Paper 2 style · calculator · 6 marks
(a)For the curve y = 4 tan(x/2), where x is in radians and −π < x < 3π, state the period and the equations of the asymptotes.[3]
(b)Find the value of y when x = 2π/3, giving your answer correct to 3 significant figures.[1]
(c)Find the values of x in the interval for which y = −4.[2]
Show answer
(a) period 2π; asymptotes x = π (and only that one in this interval)
period π ÷ ½ = 2π B1; asymptotes where x/2 = π/2 + nπ, i.e. x = π + 2nπ M1; in −π < x < 3π only x = π A1
Q20Trigonometric graphs · Challenge · Paper 1 style · no calculator · 5 marks
(a)The curve y = 5 cos 2x − 2 is drawn for 0 ≤ x ≤ π. State the coordinates of its end points and of its minimum point.[2]
(b)Find the set of values of k for which the equation 5 cos 2x − 2 = k has exactly two roots for 0 ≤ x ≤ π.[3]
Show answer
(a) (0, 3), (π, 3); minimum (π/2, −7)
B1 end points; B1 minimum
(b) −7 < k ≤ 3
The line y = k cuts the curve twice when it lies between the minimum and the maximum M1; k = −7 gives one root (x = π/2) A1; k = 3 gives x = 0 and x = π, two roots, so −7 < k ≤ 3 A1
Q21Trigonometric graphs · Challenge · Paper 1 style · no calculator · 7 marks
(a)Describe the curve y = |2 sin x − 1| for 0° ≤ x ≤ 360°: state the points where it meets the x-axis, the y-intercept, and the greatest value of y and where it occurs.[4]
(b)Hence state the number of solutions of |2 sin x − 1| = 1 for 0° ≤ x ≤ 360°, and find them.[3]
Show answer
(a) meets x-axis at (30°, 0) and (150°, 0); y-intercept (0°, 1); greatest value 3 at x = 270°
B1 zeros (2 sin x = 1); B1 y-intercept |−1| = 1; B1 greatest value 3; B1 at 270° (sin x = −1)
(b) 4 solutions: 0°, 90°, 180°, 360°
2 sin x − 1 = 1 → sin x = 1 → 90° B1; 2 sin x − 1 = −1 → sin x = 0 → 0°, 180°, 360° B1; 4 solutions B1
Q22Identities and proofs · Core · Paper 1 style · no calculator · 3 marks
(a)Prove that (1 + cos x)(cosec x − cot x) ≡ sin x.[3]
Show answer
(a) Proof
cosec x − cot x = (1 − cos x)/sin x M1; (1 + cos x)(1 − cos x)/sin x = (1 − cos²x)/sin x M1; = sin²x/sin x = sin x A1
Q23Identities and proofs · Core · Paper 1 style · no calculator · 3 marks
(a)Prove that tan x + cot x ≡ sec x cosec x.[3]
Show answer
(a) Proof
sin x/cos x + cos x/sin x M1; = (sin²x + cos²x)/(sin x cos x) M1; = 1/(sin x cos x) = sec x cosec x A1
Q24Identities and proofs · Standard · Paper 2 style · calculator · 5 marks
(a)Show that (sec x − cos x)/tan x ≡ sin x.[3]
(b)Hence solve (sec x − cos x)/tan x = −0.6 for 0° < x < 360°. Give your answers correct to 1 decimal place.[2]
Show answer
(a) Shown
sec x − cos x = (1 − cos²x)/cos x = sin²x/cos x M1 A1; ÷ (sin x/cos x) gives sin x A1
(b) x = 216.9°, 323.1°
sin x = −0.6 M1; 216.9°, 323.1° A1
Q25Identities and proofs · Standard · Paper 2 style · calculator · 5 marks
(a)Show that cosec²θ/cot θ − cot θ ≡ tan θ.[3]
(b)Hence solve cosec²θ/cot θ − cot θ = 3 for 0° < θ < 360°. Give your answers correct to 1 decimal place.[2]