## BLOG-103

a) Click

**here**for "01-Degree-2-Degree-Minute-Second-n-Radian-converter"
b) Click

**here**for "02-Degree-Minute-Second-2-Degree-n-Radian-converter"
c) Click

**here**for "03-Radian-2-Degree-n-Degree-Minute-Second-converter"**1) Directed Angles:**

The
initial arm rotates through certain amount of rotation in clockwise or
anti-clockwise direction to the terminal arm then
this amount of rotation is called as the measure of directed angle and such an
angle is called as

**directed****angle**.
The
directed angle AOB has ray OA as an initial arm and ray OB as the terminal arm.
O is called as

**vertex**of an angle AOB.
Note:

1)
Here, Angle AOB ≠ Angle BOA even if they have same amount of rotation.

2) If the
rotation of initial arm is anticlockwise, the directed angle is

**positive****and if it is clockwise then the angle is****negative**.See the figure carefully to understand the concept.

**2) The Zero Angles:**

The amount
of rotation of ray OA about O is zero then the directed angle is called

**zero angle**. (Here initial arm OA and the terminal arm OB coincide).**3) The Straight Angles:**

If an
initial ray OA and the terminal ray OB are opposite rays then the directed
angle is called

**Straight****angle**.**4) Degree measure:**

Here an angle is measured in degree.

(1/360)

^{th}part of a complete rotation is called as**one degree**and is denoted by 1^{0}
(1/60)

^{th}part of a complete rotation is called as**one minute**and if denoted by 1^{'}
(1/60)

^{th}part of a complete rotation is called as**one second**and if denoted by 1"**5) Radian measure:**

Here an
angle is measured in radian.

Let r be
the radius of a circle with center O. A and B are any two points on
the circle with arc length equal to radius r. Then the measure of the central
angle AOB is of measure 1 radian and is denoted by 1

^{c.}

**6) Relation between radian measure and degree measure:**

1

^{0 }= (π/180)^{ c }= 0.01745^{ c }approximately.
1

^{c }= (180/π)^{ 0 }= 57.295828^{0}
1

^{c }= (180/π)^{ 0 }= 57^{0 }17' 48"
a) Click

**here**for "01-Degree-2-Degree-Minute-Second-n-Radian-converter"
b) Click

**here**for "02-Degree-Minute-Second-2-Degree-n-Radian-converter"
c) Click

**here**for "03-Radian-2-Degree-n-Degree-Minute-Second-converter"
Remaining part will be published in the next blog.