Step 1)  Create a new sketch on the front plane. There should only be 1 sketch that you use

Step 2)  Create a circle and then use the “coincident ” button to center it on the origin by clicking on the origin, the center of the circle :

 

Step 3) make its radius 15 MM by using the dimension tool

Here’s what your document should now look like :

Step 4)  Do the same thing with a second circle . Make its radius 30

Picture: 

Step 5) Make a line that touches the circle, anywhere. Like the picture below:

 

 

Step 5) Find the “tangent line”  constraint (this might be a dropdown)

 

Step 6) Here’s how you create a tangent line.

Click the circle , click the line you made, then press “tangent line ”

 

Step 7)  Make a construction line from the tangent line to the bottom

 

Step  8) Make a second tangent line as shown:

 

Step 8) Dimension both tangent lines so that they are 60 MM each

 

Step 9) Add a second shape that is dimensioned.