Applets
The word Trigonometry is derived from the greek words , 'Trigon' and 'Metron' and it means 'Measuring the sides of a triangle'. The subject was originally developed to solve geometric problems involving triangles. It was studied by sea captians for navigation, surveyor to map out the new lands, by engineers and others. Currently Trigonometry isused in many areas such as the Science of seismology , designing electric circuits, describing the state atom, predicting the heights of tides in the ocean, analysing a musical tone and in many other areas.
Angle
Angle is a measure of rotation of a given ray about its initial point. The original ray is called the initial side and the final position of the ray after rotation is called the terminal side of the angle. The point of rotation is called the vertex. If the direction of rotation is anticlockwise, the angle is positive and if the direction of rotation is clckwise, the angle is negative.
If a rotation from the initial side to terminal side is (1/360)th of a revolution, the angle is said to have a measure of one degree written as 1o. A degree is divided into 60 minutes, and a minute is divided into 60 seconds . A minute is written as 1' and a second is written as 1'' .
1o= 60' and 1'= 60''
One radian is defined as angle subtended by arc , whose length is equal to its radius. One radian is denoted by 1c.
Relation between degree and radian
Since a circle subtends at the centre an angle whose radian measure is 2π its degree measure is 3600
ie., 2π radian = 3600 or
π radian = 1800
Using approximatevalue of π as 22/7 ,we have
1 radian = 180/π ≈ 57016'
10= π/180 radian ≈ 0.01746 radian
Applet
Vector Algebra
In our day to day life, we come across many queries such as - What is your height ? How should a football player hit the ball to give a pass to another player of his team? The possible answer to the first query may be 1.6m or 1.4m...- a quantity that involves only one value (magnitude) which is a real number. Such numbers are called scalars. However, an answer to the second query is a quantity (force) which involves muscular strength (magnitude) and direction (in which another player is positioned). Such quantities are called vectors. ie, A quantity that has magnitude as well direction is called a vector.
