Key learning points

1. The cosine ratio involves the hypotenuse, adjacent and the angle
2. If you know the length of the hypotenuse and the size of the angle, you can use the cosine ratio
3. If you know the length of the adjacent and the size of the angle, you can use the cosine ratio
4. If you know the length of the hypotenuse and adjacent, you can use the cosine ratio

Keywords

• Hypotenuse - The hypotenuse is the side of a right-angled triangle which is opposite the right angle.

• Adjacent - The adjacent side of a right-angled triangle is the side which is next to both the right angle and the marked angle.

• Trigonometric functions - Trigonometric functions are commonly defined as ratios of two sides of a right-angled triangle containing the angle.

• Cosine function - The cosine of an angle (cos(θ°)) is the x-coordinate of point P on the triangle formed inside the unit circle.

Common misconception