Angle x is acute, and sin(x) = 5/13. Find the exact value of cos(x).
(Total for Question 3 is 2 marks)
4
Simplify sin2(x) + cos2(x) - 3.
(Total for Question 4 is 1 mark)
5
State the value of x, with 0 ≤ x ≤ 180, for which sin(x) = 1.
(Total for Question 5 is 1 mark)
6
Which of the following is equivalent to 1 - sin2(x)?
A) cos2(x)
B) tan2(x)
C) -cos2(x)
D) sin2(x) - 1
(Total for Question 6 is 1 mark)
7
Solve tan(x) = 1 for 0 ≤ x ≤ 180.
(Total for Question 7 is 1 mark)
8
Solve sin(x) = 0.5 for 0 ≤ x ≤ 360, giving all solutions.
(Total for Question 8 is 2 marks)
9
Solve cos(x) = -0.5 for 0 ≤ x ≤ 360, giving all solutions.
(Total for Question 9 is 2 marks)
10
Given that cos(x) = 4/5 and x is acute, find the exact value of tan(x).
(Total for Question 10 is 2 marks)
11
Show that (1 - sin2(x))/cos(x) = cos(x), for cos(x) not equal to 0.
(Total for Question 11 is 2 marks)
12
State the value of sin2(30 degrees) + cos2(30 degrees).
(Total for Question 12 is 1 mark)
13
Solve 2cos(x) = 1 for 0 ≤ x ≤ 360, giving all solutions.
(Total for Question 13 is 2 marks)
14
Solve 5cos(x) = 2 for 0 ≤ x ≤ 360, giving your answers correct to 1 decimal place.
(Total for Question 14 is 3 marks)
15
Given that sin(θ) = 0.6, where θ is obtuse (90 < θ < 180), use sin2(θ) + cos2(θ) = 1 to find the value of cos(θ).
(Total for Question 15 is 3 marks)
16
Prove that (1 + sin(x))(1 - sin(x)) = cos2(x) for all values of x.
(Total for Question 16 is 3 marks)
17
A ramp makes an angle x with the horizontal, where 0 < x < 90, and satisfies 3sin(x) = 2cos(x). Find the exact value of tan(x), and hence find x, giving your answer correct to 1 decimal place.
(Total for Question 17 is 3 marks)
18
Solve 2cos2(x) + 3cos(x) - 2 = 0 for 0 ≤ x ≤ 360, giving all solutions.
(Total for Question 18 is 4 marks)
19
A force vector makes an angle x with a reference axis, where sin(x) + cos(x) = 7/5.
(a)Show that 2sin(x)cos(x) = 24/25.(3)
(b)Hence find the value of (sin(x) - cos(x))2.(2)
(Total for Question 19 is 5 marks)
Mark scheme · G3D Further Trigonometric Identities and Equations: Fluency and Exam Drill
Question 1
B1√2/2 oe (e.g. 1/√2)
Answer: √2/2
Question 2
B1√3 oe
Answer: √3
Question 3
M1 use sin2(x) + cos2(x) = 1 to get cos2(x) = 1 - (5/13)2 = 144/169
A1 cos(x) = 12/13 (positive root, since x is acute), cso
Answer: 12/13
Question 4
B1 -2 cao
Answer: -2
Question 5
B1 x = 90 cao
Answer: x = 90
Question 6
B1 A) cos2(x)
Answer: A) cos2(x)
Question 7
B1 x = 45 cao (the next solution, 225, lies outside the given range)
Answer: x = 45
Question 8
M1 arcsin(0.5) = 30 (principal value)
A1 x = 30 and x = 150 (using 180 - 30), both required cao
Answer: x = 30, 150
Question 9
M1 reference angle arccos(0.5) = 60, and recognises cosine is negative in the second and third quadrants
A1 x = 120 and x = 240, both required cao
Answer: x = 120, 240
Question 10
M1 use sin2(x) + cos2(x) = 1 to find sin(x) = 3/5 (positive root, since x is acute)
A1 tan(x) = 3/4 oe cao
Answer: 3/4
Question 11
M1 use sin2(x) + cos2(x) = 1 to write 1 - sin2(x) = cos2(x)