Cosine of an angle is a ratio between the side adjacent to the angle and the hypotenuse of a triangle.

Cosine is one of three trigonometric functions of an angle.

cos(x) is found by calculating the ratio of two sides of a right-angled triangle, the adjacent and the hypotenuse.

The diagram shows a cosine graph.

1

Find a if cosB = 0.9 and c = 40.

2

Find the value of A in the triangle shown.

3

Find a if cosB = 0.3 and c = 20 cm.

4

Find the length of the line p in the triangle shown.

5

Write down the coordinates of point B on the cosine graph.