How to make the perfect pizza shape from a circle using the pen tool?

Question

How can I make a perfect pizza shape from a circle using the pen tool?

Say I have the below circle shape.

I of course want a pizza shape like below:

But the angle on the left and the right should be exactly the same. (It looks the same in the image but I actually eye balled it.) Is there a "snap to X" that will tell me how far the pen is from the center point of the circle?

I know this can be achieved using the shape tool -> align the triangle on top of the circle -> select both -> divide from shape (or think subtract).

However I want to do this using the pen tool.

Answer 1

You don't actually need to use the pen tool for that. The Circle tool options have a Slice function which includes a start and end field into which you can type the angles.

The top node of a circle is placed at 270 degrees, so for example if you need an angle of 50 degrees, then type "270-25" into the Start field, and "270+25" into the End field.

Example

If you still want to use the pen tool, then you could do it with a grid, and snap to grid, draw a triangle

Then select both the circle and triangle and do Path > Intersection

Answer 2

It's possible, the circle can also be drawn with the pen. Inkscape's pen has Spiro path mode in the option bar. Select it to make approximately right circles:

This needed 3 clicks. One in the midpoint, the 2nd to 11 o'clock and the last one to close the curve at 5 o'clock.

Duplicate the result (=Ctrl+D). Flip it horizontally.

Set all point snaps on, also the midpoint snap.

Set for the pen the normal Bezier curve mode ON. Draw the V shown in the next image from 11 to center to 1 o'clock. It needs 3 clicks and one right click to stop the drawing.

Select the V and one of the circles. Apply Path > Division and drag the slice apart:

Here's another way - just for fun and knowing better the tools. It also needs point snaps = ON

1. You have a circle. Draw a line with the pen across the circle. Hold Ctrl to get it horizontal, if that's needed. Draw a line which starts from the centerpoint. Its direction and length can be arbitary, but I drew a radius to the crossing (=blue). You need the line only to remember the center. To get it right you must have centerpoint snap =ON.

2. Select the horizontal line and the circle. Separate the circle segment by applying Path > Division, remove the bottom part.

3. Double-click the horizontal line somewhere with the node tool to create a new node. Drag that node to the center. Delete the extra line (=blue).

BTW. No need to divide the circle. You can as well convert it to path (=Path > Object to Path) and insert with the node tool new nodes to the ends of the wanted slice edge. Then you delete the unnecessary nodes of the circle and shorten the handles, You have the same circle segment as you got by dividing with a line.