Quick tricks to draw a tangent to a circle.

[FixitMike]

Draw a vector from the desired tangent point on the circle through the center of the circle. Then rotate that line 90 degrees around the end that is on the circle to make the tangent.

To draw a tangent to a circle from a point: Use the circle tool. Click on the point and drag the circle so it passes through the center of the original circle. ( Optional: Trim the constructed circle to the original circle.) Draw the tangent vector from the point to the intersection of the two circles.

Be sure the Edit, Snap Options, Snap Guides to Geometry box is checked.

[mtylerfl]

Hi Mike,

Maybe a screenshot or two will help us understand this tip a little better. I generally use the Circle Tangent Gadget for this type of thing for generating tangents between two circles, but your tip sounds intriguing!

[sawmillsam]

Mike, I think that is a wrong description of the method. The link below shows the correct method.

https://www.mathsisfun.com/geometry/con ... ngent.html

Basically, to draw a line tangent to a circle from a point, draw a line from the point to the center of the circle.

Bisect that line and from that midpoint draw a circle that goes through the center of the original circle. Where the circles intersect are the tangent points.

[FixitMike]

Mea Culpa. Sawmillsam, you are absolutely right.

Mike, I think that is a wrong description of the method. The link below shows the correct method.
https://www.mathsisfun.com/geometry/con ... ngent.html

Basically, to draw a line tangent to a circle from a point, draw a line from the point to the center of the circle.

Bisect that line and from that midpoint draw a circle that goes through the center of the original circle. Where the circles intersect are the tangent points.

[dhellew2]

Another way, if you know the desired angle of the vector line...
snap a line start point at the center of the circle
draw the line outwards at the desired angle
then offset the line outwards at the radius of the circle
use the scissor tool and clip the lines
The line will then be tangent to the curve of the circle

Dale