# Thread: Atan and Atan2 (2003, xp)

1. ## Atan and Atan2 (2003, xp)

Can any one tell me.
why we use Atan and Atan2 function?
How can we use these functions?
What is the logic behind to use these function?
what is the importance of these functions?
The defination inside excel did not help to clear my concept so want a favorable response from your side.
Thankyou.
with kind regards

2. ## Re: Atan and Atan2 (2003, xp)

ATAN and ATAN2 are mathematical functions, used in trigonometry.

ATAN is the inverse of the TAN or tangent function.
In the picture below, AB ~ 3.4 and BC ~ 5.4. The tangent of the angle at A is BC / AB ~ 1.59.
Conversely, the angle at A is ATAN(1.59) ~ 1 radians ~ 57 degrees.

ATAN2 is used when you know the sides of the triangle and want to compute the angle: the angle at A is ATAN2(AB,BC) = ATAN2(3.4,5.4) ~ 1 radians ~ 57 degrees.

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•