** Initial side and terminal side angle**:Two rays with a common starting point from an angle and the other is terminal side. The angle is identified by showing the direction of rotation from the initial side to the terminal side.

**Positive angle:**

Anti-clockwise rotation angle is always positive(+tive) angle.

**Negative Angle:**

Clockwise rotation Angle is always Negative (-tive) Angle

An angle is said to be positive or negative if the rotation is clockwise or anticlockwise.

**Angle Notation:**

Angle are usually denoted by Greek letter

such that

Alpha = α

Beta =β

Gamma =γ

theta = θ

**Trigonometry mean**:

The word Trigonometry has been derived from three Greek word **Trei**(three),** GONI**(angles)** and Metron**(measurement). Usually it means measurement of triangle.

**Use of Trigonometry:**

Trigonometry formula use in calculus problem, algebra problem, in physics and many branches of science.

**Uses of daily life problem:**

Trigonometry use in daily life real problem example land area, distance of walk, measure the area of building, and it is use geography, road map distance, and use in spacer distance.

**Use of Atomic:**

Trigonometry use in atomic technology, trigonometry fixed formula in atom, Marine, tank.

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