SPM 2017 Add Maths Paper 1, Question 14Trigonometric Functions

Solved on video in English and Bahasa Melayu · 3 marks · Form 5, Trigonometric Functions · 3:51 video

The question

Diagram 6 shows the graph of y = m cos px - 1 for 0 <= x <= pi. State (a) the value of (i) m, (ii) p, (b) the number of solutions for m cos px = -3.

[3 marks]

Step 1

At x = 0, y = 2 (from the graph): m cos(0) - 1 = 2, i.e. m(1) - 1 = 2, so m = 3.

Why this step

At x = 0, cos(0) = 1 whatever p is, so p disappears and only m is left. Read y = 2 carefully off the graph.

3 more steps, each with the reason for it, in the full solution

Final answer

m = 3, p = 2, 1 solution

Where students lose marks

Watch out: the graph is shifted down 1, so m cos(px) = −3 means y = −4 on the graph, not y = −3.

Watch every step of this question solved on video (3:51), with the reason behind each step and a box that checks your own answer.

No card. Every past-year question on video, in English and BM.