# Question regarding variable name

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#### Dr.Peterson

##### Elite Member
Hi, in the below matrix, can someone please tell me what the 'c' represents? and what is the sub symbol next to it?
View attachment 25221
source: https://en.wikipedia.org/wiki/Rotation_matrix
When you see an unfamiliar symbol, always look just before or after its first appearance for the definition!

Here is your snip, with one more line of context:

Now, can you tell me what $$c_\theta$$ means?

They are just abbreviating, to reduce the size of this monster. I often write just c and s for the same purpose in the middle of a long calculation.

#### markraz

##### Full Member
When you see an unfamiliar symbol, always look just before or after its first appearance for the definition!

Here is your snip, with one more line of context:

View attachment 25224

Now, can you tell me what $$c_\theta$$ means?

They are just abbreviating, to reduce the size of this monster. I often write just c and s for the same purpose in the middle of a long calculation.
Theta?

#### Dr.Peterson

##### Elite Member
Yes, $$c_\theta$$, with subscript theta, is the cosine of the angle theta by which something is rotated. And $$s_\theta = \sin(\theta)$$.

#### markraz

##### Full Member
Yes, $$c_\theta$$, with subscript theta, is the cosine of the angle theta by which something is rotated. And $$s_\theta = \sin(\theta)$$.
ooooh dunce cap lol... I'm slow.....Thanks for your help appreciate it

Last edited:

#### Subhotosh Khan

##### Super Moderator
Staff member
ooooh dunce cap lol... I'm slow.....Thanks for your help appreciate it
Here we send people to the "corner" - and sit there for a while facing the walls.

If you need direction to the corner - ask Jomo.