(a) Copy and complete the table of the relation (y = 2sin x – cos 2x).
| x | 0° | 30° | 60° | 90° | 120° | 150° | 180° |
| y | 0.5 | -1.0 |
Using a scale of 2 cm to 30° on the x- axis and 2 cm to 0.5 unit on the y- axis, draw the graph of (y = 2sin x – cos 2x), for (0° leq x leq 180°).
(b) Using the same axes, draw the graph of (y = 1.25).
(c) Use your graphs to find the : (i) values of x for which (2sin x – cos 2x = 0) ; (ii) the roots of the equation (2sin x – cos 2x = 1.25).
Explanation
(a) (y = 2sin x – cos 2x)
| x | 0° | 30° | 60° | 90° | 120° | 150° | 180° |
| y | -1.0 | 0.5 | 2.2 | 3.0 | 2.2 | 0.5 | -1.0 |
(b)