# I need help finding the length?

#### sjm

##### New member
Hi All,

I am looking for help finding the length shown in image below.

I know the radius of the circle. This is 442.5. I also know the angle although this will vary and I will calculate the length dynamically.

Any help appreciated.

#### lev888

##### Senior Member
There is a triangle that should be useful. Which sides and angles do you know? Can you express the length of the side you need as a function of the given angle?

#### Jomo

##### Elite Member
Are those two red lines parallel?
Are the two black lines parallel?

#### sjm

##### New member
I know this site is designed for helping people learn maths. However my situation is different I have a problem at work and just need some help.

The two red lines are parallel. The two black lines are in fact dimension leader lines but yes also parallel.

#### Subhotosh Khan

##### Super Moderator
Staff member
I know this site is designed for helping people learn maths. However my situation is different I have a problem at work and just need some help.

The two red lines are parallel. The two black lines are in fact dimension leader lines but yes also parallel.

Do you know laws of sines for triangles?

#### sjm

##### New member
I studied Trigonometry at school but that was a long time ago and I no longer remember it.

#### Jomo

##### Elite Member
If you want help, then we have no problem helping you get the answer. However we will not just outright do the problem for you.

This problem is as simple as knowing the definition of secant(x) = hypotenuse/adjacent. You have one red triangle which has a 90 degree angle. You can easily figure out the angle by the center of the circle. Using secant you can find the length of the hypotenuse which is the same length as the side which you want.

#### hoosie

##### Junior Member
To help with your understanding of how to solve the problem I have outlined some steps to follow:

#### Subhotosh Khan

##### Super Moderator
Staff member
@sjm - If I said: