In mastercam there is a feature which you can connect 2 circles with a tangent line that are automatically calculate the coordinate on BOTH CIRCLES and becomes the arc tangent for BOTH circle that you select. Then, you can enter the dimension for that tangent line.

In solidworks, I'm trying to connect 2 circle with a tangent line but turn out it doesnt automatically calculate and when i entered the dimension for the tangent line, it changed the dimension of the circle to fit the tangent line. Anyone know how to solve this problem. please help.

Your book image is missing a dimension. I had to make the assumption that the vertical construction line = 15.

You really should attach your *.sldprt file here if you want the best help.

To attach a *.sldprt file here - Reply to response and then click Advanced Editor in the upper right corner of reply dialog box.