Recognise and sketch y=sinx, y=cosx, y=tanx and y=kx, and use their symmetry to find values. It is Higher only, aimed at grade 7. Free questions with answers are on this page.
Know the standard shapes: y=sinx and y=cosx oscillate between −1 and 1 with period 360∘; y=tanx has period 180∘ and vertical asymptotes at 90∘,270∘,…. y=ax (exponential growth for a>1) gets steep and never goes negative; y=a−x decays. y=sinx passes through (0,0); y=cosx through (0,1).
Transformations later will stretch these; here you sketch the parent, mark the key intercepts and turning points, and read solutions of sinx=0.5 as the x-values where the graph is at height 0.5 (two in 0∘ to 360∘ for sin).
sin and cos oscillate between −1 and 1; tan repeats every 180∘ and has asymptotes. y=2x always passes through (0,1). CAST / the graph gives the second solution in 0∘ to 360∘.
Objectives
Read sin and cos at the key angles.
Read tan 45 and the period of sine.
Read powers of 2 from the exponential graph.
Key points
Sketch the sine and cosine curves from 0∘ to 360∘ with the key points marked.
Sketch y=tanx with its asymptotes at 90∘ and 270∘.
Use symmetry to find a second solution of sinx=a or cosx=a in a given range.
Sketch y=kx for k>1, knowing it passes through (0,1) and never touches the x-axis.
Worked examples
Example 1
On the sine graph, find the value at 90 degrees.
2 marks
Identify that sine reaches its maximum peak at 90 degrees.
Read the peak value on the y-axis: 1.
State the value is 1.
Answer: 1
Common slips
Slip: Assume value is 0. Sine starts at 0 and rises to 1 at 90 degrees.
Slip: Read -1. The peak above the axis has positive height 1.
Slip: Write 0. sin 90° = 1.
Example 2
On the cosine graph, find the value at 180 degrees.
2 marks
Trace cosine curve from (0, 1) through (90, 0) to 180 degrees.
Read the minimum trough value: -1.
State the value is -1.
Answer: -1
Common slips
Slip: Stop at 90 degrees. Cosine continues downward past the x-axis.
Slip: Read 0. Cosine reaches its lowest point at 180 degrees.
Slip: Write 1. cos 180° = -1.
Example 3
On the exponential graph, find the value of 2⁰.
3 marks
Apply zero power rule: any non-zero base raised to power 0 equals 1.
Locate x = 0 on the curve: y = 1.
State the value is 1.
Answer: 1
Common slips
Slip: Assume power 0 gives 0. 2⁰ = 1, which is the y-intercept of y = 2^x.
Slip: Read y = 2. The graph crosses the y-axis at (0, 1).
Slip: Write 0. 2⁰ = 1.
Questions and answers
GCSE Maths trigonometric & exponential graphs questions and answers. Try each one, then open the answer. Easy questions come first.
Question 1 Easy2 marks
On the sine graph, find the value at 180 degrees.
Show answer
Answer: 0
Sine crosses the x-axis at 180 degrees.
Value is 0.
M1 — Sine crosses the x-axis at 180 degrees.
A1 — Value is 0.
Question 2 Easy2 marks
On the sine graph, find the value at 270 degrees.
Show answer
Answer: -1
Sine reaches its minimum trough at 270 degrees.
Value is -1.
M1 — Sine reaches its minimum trough at 270 degrees.
A1 — Value is -1.
Question 3 Medium2 marks
On the cosine graph, find the value at 60 degrees.
Show answer
Answer: 1/2
cos 60 = 1/2.
Value is 1/2.
M1 — cos 60 = 1/2.
A1 — Value is 1/2.
Question 4 Medium2 marks
On the tangent graph, find the value at 45 degrees.
Show answer
Answer: 1
tan 45 = 1.
Value is 1.
M1 — tan 45 = 1.
A1 — Value is 1.
Question 5 Hard2 marks
On the exponential graph, find the value of 2⁵.
Show answer
Answer: 32
2⁵ = 16 × 2.
Value is 32.
M1 — 2⁵ = 16 × 2.
A1 — Value is 32.
Question 6 Hard2 marks
What is the period of the sine graph in degrees?
Show answer
Answer: 360
The wave repeats every 360 degrees.
Period is 360.
M1 — The wave repeats every 360 degrees.
A1 — Period is 360.
Question 7 Exam-style4 marks
Write down the value of (a) cos 270°, (b) tan 45°, (c) 2⁵, and (d) the period of the sine graph in degrees.
Show answer
Answer: 0, 1, 32 and 360
cos 270° = 0, because the cosine graph crosses the axis at 270 degrees.
tan 45° = 1.
2⁵ = 2 × 2 × 2 × 2 × 2 = 32.
The sine graph repeats every 360 degrees.
B1 — cos 270° = 0
B1 — tan 45° = 1
B1 — 2⁵ = 32
B1 — Period 360 degrees
Common mistakes
Most lost marks on this topic are one slip.
Reading sine at 180 as 1
The peak is at 90. At 180 the value is 0
Saying 2⁰ = 0
A power of 0 is 1
Giving the sine period as 180
The full repeat is 360 degrees
Spot the slip
On the sine graph, a student says the value at 180 degrees is 1. What is it?
0
1
-1
Show the slip
0 The sine graph is back on the axis at 180 degrees.
Exam tips
Be ready to do this without a calculator. Paper 1 is the non-calculator paper.
If the question says “show that”, the result is given. The marks are for the steps that reach it.
The method is the same on AQA-style and Edexcel-style papers.
Always sketch the curve, even roughly, and mark the line y=a — the sketch is your evidence for the second solution.
Label the key points (0, 90, 180, 270, 360 on the x-axis; 1 and −1 on the y-axis) on every trig sketch.
Printable worksheet
The same questions are in a PDF you can print. Answers start on a later page.