Geometry and trigonometry
An angle is formed when two straight lines meet at a point. The basis unit of angular measurement is the degree. A degree may be subdivided into smaller parts known as minutes and seconds. A radian is a unit of angular measurement that is used in some aspects of engineering science. A radian is the angle that is covered at the centre of a circle by an arc equal in length to one radius on the circumference of the circle. In a right angled triangle the following names are given to the sides of the triangle and these names are used to define the trigonometrical ratios: sine, cosine and tangent. The values of the trigonometrical ratios are a standard facility on scientific calculators and they are also given in mathematical tables.